Can a Black Ghost Fish Produce an Electric Shock?>
Updated 7/13/10

QUESTION:
Can black ghost knife fish give an electric shock?

ANSWER:
No, but black knife fish do produce an electric current.
Black Ghost Knives have a small electrode sensor near their nose to sense and smell since they have almost no use of their eyes. Black Ghost Knife fish are nocturnal and are always found looking for food at night. The sensor emits a small electric current in the water which is not felt by any other fish and will not cause any harm.

The reason the current is not felt, is that knife fish produce volts, but few amps. Even their cousin, the electric eel is capable of large voltage output, but low amps (usually around 1 amp), which is why they are not very dangerous to humans, although they can stun smaller prey.

Further Electric Eel Information

Here is some data on Electrophorus electricus, the electric eel.

*Maximum recorded voltage: 550 volts (at 1 amp). This was recorded for a 2 m long fish (the size of the fish is related to the size of the electrical discharge).

*Length of pulses: a few milliseconds, so it's not long enough to heat up the filament on a standard incandescent light bulb.

*These discharges are usually not used to kill, but to either stun prey or convince threatening organisms to go elsewhere.

*While powerful enough to knock a person down, it's extremely unlikely electric eels could kill a person.

*From: Paxton, J. R. and Eschmeyer, W. N. (Eds.). 1994. The Encyclopedia of Fishes, p. 112

For those who read this and think about all the Yahoo Answers posts and other inaccurate web articles then scratch their heads thinking, “wait, this guy is stating the opposite of what most others are stating”, well you need to deeper past all these anecdotal posts from those with little understanding of the physics of electricity that come up on Google. One such comment is “the electric eel can discharge 6 times the electric charge (power) of household current”. This is incorrect when you factor in the fact that normal household current is at 10-15 amps vs. the Electric Eel at 1 amp. For example an electric heater that uses 10 amps @ 120 volts = 1200 Watts. An electric eel at 1 amp @ 600 volts is 600 watts; as well the Electric Eel only discharges for a very short periods at this voltage (often only milliseconds).

Please see this educated web page about this subject from a professor of physics:
Electric Eel at the Aquarium

This article shows the irregularity of DC voltage as well the video in this article only show low wattage Christmas lights, not a heater or other device that would use the amount of electricity to seriously harm a human:
How Much Electricity Can an Electric Eel Produce




A Few Facts:

*Origin; Amazon and Paraguay Rivers
*Max size; 16- 20 inches
*Recommended Aquarium Size; 50 gallons (larger is even better)
*Temperature; 72- 80F
*Water Conditions; Prefers water near 7.0, but like all FW fish still needs electrolytes and calcium. VERY sensitive to poor water conditions. I recommend reading these two articles:
“Aquarium Disease Prevention”
“Why Calcium and Electrolytes are important”
*Foods; Prefers live foods (bloodworms, black worms, brine shrimp)
*Tank furnishings; Ghost Knife fish need a place to hide, a clear plastic tube provides this and allows you to still see your pet (Lee’s aquarium products makes one)
*Genus: Apteronotus
*Species: albifrons

*Related fish include the Elephant Nose Fish (Gnathonemus petersii) which have similar requirements and reach a size of approximately 10" (although from the Niger River area of West Africa)


For up to date aquarium info (especially Redox and dispelling UV myths), please visit this site:
AQUARIUM AND POND INFORMATION;
Well researched and up to date aquarium and pond answers, help, and links. Based on 30+ years of professional aquarium maintenance experience.

For an experienced aquatics forum:
Everything Aquatic

QUESTION: Do Bio Wheels really work?


ANSWER: There is a lot of information about bio wheels and their importance in bio filtration in aquariums. In theory they are great idea and I admittedly bought into this idea for years without testing the results to see if the hype was true. In theory the wheel turns into the air where oxygen the aerobic bacteria need to remove ammonia and nitrites is much more abundant. Unfortunately oxygen is not the only requirement for nitrifying bio bacteria; you also need surface area which bio wheels do have although often not nearly as much as many aquarium sponge media or ceramic bio rings. You also need nutrients and often the bacteria in bio wheels are not exposed to enough nutrients.

But after many a wheel stalling with the many customers I serviced aquariums for and after I was challenged by another person in the maintenance business after telling him I was thinking of adding some large bio wheel systems to a couple marine tanks, he asked me if I ever tested them against other filters (he had performed such tests and knew the answer). I decided to start testing these wheels vs. other bio filter methods.

In a more limited test (this is the test my colleague had performed), I removed the bio wheel on penguin filters on comparable (60 gallon) established aquariums with comparable bio loads and fish and found no discernable ammonia spike. Yet when HOB filters that had running Sponge Pre Filters attached to their intakes were removed, there were discernable ammonia spikes. What this means is that the Bio Wheel was not the primary source or even an important source of bio filtration for the tanks with the bio wheels. In other words these tanks were maintaining whatever bio filtration they had via other means such as gravel, filter cartridges, etc, while the aquariums with the Pre-Filters (& a couple with a sponge insert) had these bio filter mediums removed the loss of bio filtration via a discernable spike in ammonia/nitrites was noted.

In another second and more extensive test, I ran some tests with Penguin Filters (as well as one Emperor Filter) with Bio Wheels against Sponge Filters, Aqua Clears and Whisper Filters with the Sponge inserts in equal established tanks fed the same amount, then added large amounts of fish food and although the bio wheels did respond, the sponge filter showed a lower ammonia spike. In fact in these tests the aquariums that responded to the largest amounts of fish food were the multi-filter tanks that included a HOB Filter (such as a Whisper, VitaLife, etc.) AND a Sponge Filters which provided a good example of how much Sponge Filtration via a simple Sponge Filter can improve aquarium bio capacity.
I might add that since these initial tests/studies several years ago, that a new variation of the Wet/Dry, Sponge and HOB filter has emerged that combines the best of both filters and that is the Internal Wet/Dry such as the ReSun BF 200 or the filter found in Bio Cube Aquariums. My reason in pointing out these filter systems is that they combine many of the best attributes of the before mentioned filters which includes excellent bio filtration making this filter style an excellent choice (especially of a bio wheel equipped filter or at least as a compliment to an aquarium that already employs one)

Both these tests were not performed under the best of scientific scrutiny (although the second was much more extensive and gave a better picture of nitrifying bacterial colonies), however they certainly gave an interesting snapshot of the effectiveness of different bio filtration types.


This is not to say a bio wheel does not work at all, especially there is less build up deposits on the bio wheel fiber.
What is much more important is to have an adequate amount of dissolved oxygen through agitation of the water surface which is where oxygen and other gasses are exchanged from the atmosphere and the aquarium. I have found a porous sponge filter media to maintain more bacteria in well oxygenated water.
This is an important point as although air can contain much more oxygen necessary for aerobic nitrifying bacteria (which is the theory behind bio wheels), the fact remains that the nitrifying bacteria do quite well at the normal dissolved oxygen level of 5-7 ppm of most adequately circulated and properly stocked aquariums.
In fact a somewhat unknown filter; the fluidized filter well out performed bio wheels and wet/dry filters in test and yet they are sealed filters (this comparison is based on established filters over 6 months old).


Here are a few reasons behind the poor results of bio wheels:

[1] Hard water buildup; although not as much a problem in soft water aquariums, this is a major problem with hard water aquariums and especially marine aquariums (where these bio wheels are a total waste of money). What happens is the calcium, salts and other deposits form in the pores of the bio wheel fiber, not allowing bacteria to form there. This is the main reason for the lack of effectiveness for bio wheels. My tests in Discus aquariums (which are soft water) showed better results for bio wheels (although not as well as sponge or other porous media).

[2] Lack of surface area; a bio wheel does not have the surface of many other bio media products from sponge media to the very porous pumice and ceramic media used by Eheim and others.

[3] Bio wheel stalls; bio wheels have a bad habit of stalling or rotating too slowly for the bacteria to be bathed in nutrients. This can be only a minor reason to not have these bio wheels as this is a somewhat correctable problem.
Here is a way correct this problem (this will be an on going maintenance problem). Make sure the Teflon ends on the bio wheel axle are clean and have no build ups of calcium you can replace these with Teflon tape in a pinch. Also make sure the bio wheel assembly is not to tight, simply remove the bio wheel and gently stretch the assembly apart so the wheel can spin more freely.

SUMMARY;

This NOT to say bio wheels do not work! Bio wheels just do not hold up to the hype and urban myths about them in the aquarium hobby. You can often do better with the sponge in an Aqua Clear or Whisper, the Bio Grid on a Via Aqua VitaLife, a pre filter on any HOB filter, a separate sponge filter or even an aquarium sponge stuck inside a HOB filter without any other bio media. I have used many Bio Wheel (Penguin, Emperor, etc.) filters over the years with good results, my point is again not that they do not work, just if you are purchasing one of these filters for the main reason of having a “better” bio filter, you are not making the best choice based on controlled test data.
I also want to be clear that if you already have a Bio Wheel equipped Penguin or Emperor that I am NOT advocating that you immediately trash this filter and run down to your local fish store (or online) to purchase a new filter, rather to consider their drawbacks and I do STRONLY recommend the purchase of a filter such a Hydro Sponge Filter or Internal Wet/Dry Filter to compliment your Bio Wheel equipped filter (which I recommend for any filtration system anyway; redundancy!).

Finally, what is missed by proponents of Bio-wheels is although the oxygen aspect of the bio-wheel is one aspect of aerobic nitrification, it is not difficult to maintain adequate oxygen levels for most other aquarium bio filters in a properly set up tank. What is more important is surface area and there are many other filter medias with higher surface area than bio wheels such as many quality sponge filters, volcanic rock, ceramic media and MUCH more.
Another important aspect of aerobic filtration is that the faster and more ammonia and nitrites your aquarium bio filter processes the more nitrates your aquarium will have in the end. This is especially noteworthy for marine aquariums which is why I would recommend live rock crumbles, volcanic rock, Bio Home or similar filter media that has deep pores to perform de-nitrification via anaerobic bacteria and why my consideration many years back of a large bio wheel system for a marine tank was/is a bad one. The use of a Protein Skimmer in Marine tanks can be helpful in preventing nitrate buildup as well. Please see this article for more marine aquarium information: “Saltwater Aquarium Basics to advanced”

I will also state that the design of most Marineland (Penguin, Emperor Filters) are very efficient and they are reliable mechanical filters with much less flow-by than some others, most notably Aqua Clears, so with this in mind, ANY filter decision should be based on what you need out of a filter and for more aquarium information about aquarium filters: Aquarium Filters and Filtration

For more aquarium information, please visit this site: “AQUARIUM AND POND INFORMATION” which includes article such as Aquarium Lighting which dispells many of the myths about aquarium lighting via sound research that unfortunately prevail in the aquarium keeping community.

PROPER OSMOTIC FUNCTION- ELECTROLYTES
*The Importance of healthy Osmoregulation in fish (freshwater/saltwater)
*Information about the use of RO, DI (or Distilled), or Rain water in aquariums (including information about Reverse Osmosis units)
* Necessary Minerals
Updated 4/5/10

QUESTION: How do fish drink water?

ANSWER:
Freshwater fish absorb most of the water they need through their skin via osmosis by producing dilute urine and actively transport essential mineral ions from the surrounding water to compensate for mineral ions lost via the urine and diffusion from the gills (osmosis is the net movement of water through a selective permeable membrane from a region of low solute potential to a region of high solute potential due to their hyperosmotic environment), NOT through their gills. The gills are for respiration.

Most saltwater fish (Hagfish, Sharks, Rays differ in osmoregulation) actually drink the water the live in, as the salt in the water is constantly pulling H2O from their bodies in a reverse respiration as their tissues are hypotonic compared to surrounding water and they must ingest large volumes of water and actively excrete mineral ions (hypo-osmotic environment). Marine Bony fish (not Rays, Sharks Hagfish) maintain their osmotic concentration at about one quarter to one third that of sea water. Normally in salt/sea water, bony marine fish have a tendency to lose water from their gills due to osmosis as well through their urine. Marine fish have to drink a lot of water to make up for the loss, however, as the water contains a lot of salt (35% or approximately 1.025 specific gravity) they must remove the excess salt from their system. The sodium and chloride ions are secreted by the gills and magnesium and sulphates are excreted in urine. An important side note is this is an active process and requires much energy which is why lowering salt levels (NOT other mineral ions) can be helpful in aiding a sick bony marine fish! It is noteworthy that Hagfish, Sharks, Rays have similar concentrations of salts to that of marine bony fish, however, they also have very high concentrations of organic compounds which gives their internal fluids the same osmotic concentration as sea water so these fish due not generally benefit from lower salt levels when sick.

These different abilities explain why some fish such as catfish are sensitive to salt in the water, but this is also why some fresh water fish are helped by salt to generate a mucous slime coat on their skin which is necessary for disease prevention.

For proper osmoregulation electrolytes such as calcium, magnesium and other elements are important as well.
This is important and not realized by many aquarists (especially in freshwater), however not having these electrolytes (minerals) present in the water whether by depletion or by the use of drinking water, distilled water or RO water that has not been re-mineralized can cause problems with the fish’ ability to move fluids in and out of their bodies and in the long term resist disease.

Another note, because most freshwater fish cannot drink their surrounding water (Salmon and others are exceptions), when you place these freshwater fish in saltwater, they actually dehydrate.

Osmosis in fish;

Their cells must always be bathed in a solution having the same osmotic strength as their cytoplasm. This is one of the reasons why fish and other animals have kidneys. The exact amount of water and salt removed from their blood by the fish kidneys. The process of regulating the amounts of water and mineral salts in the blood is called osmoregulation. Fish which live in the sea (remember the sea is full of salt and other elements), but fish which live in freshwater have the opposite problem; they must get rid of excess water as fast as it gets into their bodies by osmosis. Osmosis is an important topic in biology because it provides the primary means by which water is transported into and out of cells.

Osmosis is also important in the treatment of many aquarium diseases in both freshwater and saltwater. A general breakdown in osmoregulation due to disease, poor water quality (especially the lack of essential mineral electrolytes such as Calcium, magnesium, and Sodium) is often responsible for the bloated condition that results from excess water accumulation in tissues. It is common for Fish in this condition often rapidly succumb due to loss of homeostasis (the constant internal environment), essential to carrying out metabolism and other life activities this tends to be more common among FW fish in my experience, in part due to the lack of understanding of the role that many essential minerals play in essential life processes of fish.

Generally salts (trace elements), not just sodium chloride can affect osmosis. Magnesium can also play a major role too. Calcium can affect and just as importantly be affected by proper osmotic function.
Sulfates have been shown effective in improving nutrient absorption and toxin elimination. Magnesium plays a role in the activity of more than 325 enzymes and aids in the proper assimilation of Calcium.
Often many aquarists understand how salt (sodium chloride) affects osmoregulation and the popular question of “Do fish drink?” however this is a dangerous over simplification as although sodium chloride (as often represented as sodium and chloride) are important, the lack of other essential elements including Calcium (which the absence Calcium of in fish can lose/leak substantial quantities of other minerals/salts into the water).
Here is an over simplification I read recently that is not necessarily wrong, but in misleading in that it implies salt is the only essential mineral: “They (freshwater fish) absorb water through their skin and have effective ways of excreting excess liquid to maintain the salt they need”. The implication is that the fish basically just needs to maintain salt and/or this or other minerals somehow take care of themselves. The facts are that without Calcium (as tested via GH), the fish CANNOT properly osmoregulate.

For much more information about the importance of Calcium and other electrolytes, please read this article (in particular the section about Calcium):
CALCIUM, KH, AND MAGNESIUM IN AQUARIUMS; How to maintain a Proper KH, why calcium and electrolytes are important.


FRESHWATER FISH
In freshwater, a higher electrolyte level (particularly of sodium chloride, calcium and magnesium) will help pull fluids through the body which also stimulates the natural mucous coat on fish so as to resist parasites, bacteria, and fungus. Also by pulling fluids through the body this can help with bloat, swim bladder problems, intestinal problems, and even dropsy (which I have had few problems with in clean tanks with good electrolyte/ trace element levels).

This process results in the loss of many electrolytes, some of these trace elements can be replaced by ions contained in food but by far the most common method is through the movement of a substance against an osmotic gradient through the use of energy. This usually involves the exchange of one substance for another. In the case of freshwater fish, Na+ (sodium) ions are taken from the water and ammonia ions are taken from the fish and they are exchanged. This effectively rids the fish of ammonia. Chloride ions are exchanged for carbonate ions which help in maintaining the pH of the body fluids.
This is one more important reason for adequate Calcium, carbonate (KH), & electrolyte levels
Opportunistic diseases such as Columnaris, Saprolegnia (often known as fish fungus), and Aeromonas (often the cause of Septicemia) are more easily prevented when osmoregulation is functioning properly in fish via adequate mineral levels.
However it should also be noted that before you go an dump a lot of sodium chloride (salt) in your freshwater aquarium, even for fish such as African Cichlids where this is a common practice that overuse of salt can have negative side effects such as loss of other essential elements/minerals and general osmoregulation (& is occasionally noted as a contributing factor for the condition of Malawi Bloat). Put another way, you want to achieve and Osmotic balance. I prefer to use salt in fish such as African Cichlids sparingly and then bring it “up” during times of stress or suspected disease, only to bring it to low levels such as just a 1 teaspoon per 5 gallons reserving higher salt concentrations for 30 minute “salt baths” of 1-2 teaspoons per gallon when necessary for treatment/therapy. What I (and many good research papers) find is that maintaining healthy levels of Calcium, magnesium, sodium, and Carbonates is far more important for long term osmoregulation and fish health, whether it be African Cichlids or Discus (the LACK of these other elements are often a common factor in cases of Malawi Bloat).

For much more about the correct use of salt (NaCl) in freshwater aquariums, please see this article:
“Aquarium Answers; Aquarium Salt (Sodium chloride) in Freshwater Aquariums


SALTWATER FISH
A saltwater (marine) fish in water with a slightly higher salt level will devote more molecular energy to osmoregulation; following this logic, if a fish is suffering from stress lowering the salt level will help the fish to recover. Lowering the salt level (salinity) will reduce osmotic pressure within the fish allowing it to allocate more of its molecular energy to its immune system, this will help stop the stressed fish from becoming sick and can be used to treat fish that are sick.
As well, in marine fish sometimes lowering salinity will have a reverse osmotic effect and rupture the cell wall of many parasites such as Oodinium and Cryptocaryon (this is best achieved in a 3-5 minute freshwater bath adjusted for pH).
This method of lowering the specific gravity (salt content) in saltwater to fight disease should not be taken too far. I have heard of persons being told to keep their marine aquariums at a specific gravity of 1.012 to prevent of fight disease, however this is TOO LOW. At his specific gravity (salinity), the marine fish will not have proper osmotic function (remember, marine fish drink the water around them and at this salt level they will not get the fluids and minerals being pulled properly through their bodies which can result in water retention and MUCH worse). The general specific gravity in marine aquariums should be around 1.019 to 1.022 for fish and around 1.022 to 1.025 for reef.
Be careful when lowering salinity as marine fish can generally only handle about 2 degrees of salt change per day (example; 1.025 to 1.023).
To treat parasite infections (such as Oodinium and Cryptocaryon), you can TEMPORARILY and slowly lower the specific gravity to as low as 1.010.
Be careful in lowering salinity with corals and anemones present as they cannot tolerate the lower salinity levels fish can.

ANADROMOUS, AMPHIDROMOUS, & CATADROMOUS FISH

These are fish that can migrate between fresh and saltwater.
• Anadromous fish live in the sea mostly, and then breed in fresh water such as the Pacific Salmon
• Catadromous fish live in fresh water and then breed in the sea such as freshwater eels of genus Anguilla
• Amphidromous fish move between fresh and salt water during some part of life cycle, although not for reasons of breeding such as Bull sharks in the Zambezi river of Africa and living in Lake Nicaragua of Central America.

Using Salmon as an example of how bony fish (other than sharks, rays, true eels) osmoregulate in these dual conditions;

Salmon spend most of their life in the open ocean, where they reach sexual maturity, but lay their eggs gravel beds at the upper reaches of freshwater streams. When the eggs hatch, the young salmon spend several months migrating downstream to the ocean where they remain for some 3-5 years. When mature, the adult salmon return to mouth of stream where they hatched migrating upstream to its headwaters, spawn, and die.
There are osmoregulation/ physiological challenges presented by habitats as different as freshwater streams and the open ocean for which the salmon must adapt to so as to complete this cycle. The salmon uses adaptations, both behavioral and physiological, that allow it to thrive in both fresh and salt water habitats. To offset the dehydrating effects of salt water, the salmon drinks copious amounts of saltwater so as an ocean-dwelling salmon drinks, it takes in a lot of NaCl, which exacerbates the salt-loading problem. However in fresh water the salmon doesn't drink at all.
Kidney function also differs between the two habitats. In fresh water, the salmon's kidneys produce large volumes of dilute urine (to cope with all of the water that's diffusing into the salmon's body fluids), while in the ocean environment, the kidneys' urine production rates drop dramatically and the urine is as concentrated as the kidneys can make it. The result of this is that the salmon is using relatively little water to get rid of all of the excess ions it can.
Finally, the other adaptation salmon use to deal with the NaCl fluxes driven by the gradients between the salmon and its surroundings. In their gill epithelial cells, salmon have a special enzyme that hydrolyzes ATP (Adenosine triphosphate (ATP) is the universal unit of energy used in all living cells ) and uses the released energy to actively transport both Na+ and Cl- against their concentration gradients. In the ocean, these Na+-Cl- adenosine triphosphatase molecules 'pump' Na+ and Cl- out of the salmon's blood into the salt water flowing over the gills, thereby causing NaCl to be lost to the water and offsetting the continuous influx of NaCl. In fresh water, these same Na+-Cl- adenosine triphosphatase molecules 'pump' Na+ and Cl- out of the water flowing over the gills and into the salmon's blood, thereby offsetting the continuous diffusion-driven loss of NaCl that the salmon is subject to in fresh water habitats with their extremely low NaCl concentrations.

When a young salmon on its seaward journey first reaches the saline water at the mouth of its home stream, it remains there for a period of several days to weeks, gradually moving into saltier water as it acclimates. During this time, it begins drinking the water it's swimming in, its kidneys start producing a concentrated, low-volume urine, and the NaCl pumps in its gills literally reverse the direction that they move NaCl (so that they're now pumping NaCl out of the blood and into the surrounding water.
Likewise, when an adult salmon is ready to spawn and reaches the mouth of its home stream, it once again remains in the brackish water zone of the stream's mouth until it is able to reverse the changes it made as a juvenile invading the ocean for the first time.

Further reference:
http://www.unm.edu/~toolson/salmon_osmoregulation.html

RO (REVERSE OSMOSIS), DI (DI-IONIZED or DISTILLED), RAINWATER IN AQUARIUMS, OR WATER SOFTENER WATER

*First what is RO water? RO/Reverse Osmosis water is simply water that is run under pressure through a micron pre-filter, then a carbon pre-filter & finally a osmonic membrane.
The membrane is the most expensive part of a RO unit and is rated in gallons per day (gpd). With water that is too hot or cold (the ideal operating temperature is between 70-80 F or 21-27 C), along with low water pressure (psi), and high TDS (total dissolved solids) all will combine to slow the rated capacity of a RO Unit & membrane (high TDS will also affect the life of the membrane).
Often the pressure provided by the tap water is adequate, however with high capacity RO Units additional boost pumps are required (usually units over 100 gpd which require 65 to 80 psi).
Most aquarium RO units use TFC (thin film composite) membranes (the other type is the CTA, a.k.a. the cellulose triacetate membrane). Both membranes are damaged by chlorine, which is one reason for the carbon pre-filter (canister). The membrane should be changed every 2-3 years or 12,000-18,000 of total water produced (whichever occurs first).

Generally speaking, a well maintained RO unit will reject about 97% of TDS.

See this pdf site for further directions as to maintenance of a RO unit:
Pure-Flo Reverse Osmosis Instructions

*DI Unit; most commercially available DI units are simply a RO unit with an additional DI canister/chamber following the RO membrane (API makes a basic DI only unit though). This chamber utilizes resins that further remove TDS from water.
With this system, you can achieve TDS of 0 after starting with tap water over 250 TDS, while this same tap water run through a RO only unit would generally result in about 7 TDS.
For my purposes I found that a RO only unit was more than adequate, however if you are making water for extremely sensitive purposes (such as a car battery), a DI/RO unit may be the better choice for you over a RO only unit.

Another method to prepare DI Water is to distil the water by boiling then collecting the condensation of this water (AKA distilling).
This can be an economical DIY project or there are commercial water distillers also available.
If you are making a DIY Water Distiller, make sure to use condensation collection coils & other related surfaces that will not add elements back into the water, especially copper coils (which can defeat the purpose of the water distiller). Some plastics can also add chemicals back into your water, generally stainless steel is accepted to be the best surface to use for condensation collection.
Please click on the picture to enlarge


Use of RO/DI water in Aquariums;
The use of RO or DI water in aquariums should be restricted to blending with tap or well water to have a lower naturally buffer aquarium for Amazon River or similar fish. Generally I start with 25% and work up from this over time. The reason is that RO and similar water is NOT properly mineralized for correct osmoregulation with essential minerals such as calcium nor is there any carbonate buffers to maintain a stable pH which the lack there of would result in a roller coaster pH in the aquarium, often with disastrous results.
For proper osmotic function trace amounts (and I mean TRACE amounts) of several minerals are required, many supplied simply by water changes and supplements such as Wonder Shells. For this reason pure RO (Reverse Osmosis) or Distilled water are not good for water changes unless re-mineralized (with products such as Wonder Shells , SeaChem Replenish and buffers) or blended with tap or well water that is possibly too high in many minerals (a very high GH can slow respiration in some freshwater fish).
Also be real careful with water label “Drinking Water” (products such as Aquafina are simply RO water that has some minerals added for flavor for human consumption) as this is usually just RO water with a few minerals added for taste and does NOT have the electrolytes needed by fish. Usually pure spring water does have the proper electrolytes needed by fish.

I have seen many (especially on the internet) recommend rain water be used in place of tap water or similar, the reasoning is similar as with RO water that this water is more pure and therefore more healthy for the fish. HOWEVER this reasoning is severely and dangerously flawed as rainwater has NO essential minerals for osmoregulation and as well as buffering capacity at all for maintaining a stable pH (rainwater tends towards the acid side on the pH scale) which will result in a rollercoaster pH in the aquarium. Please note that the pH scale is logarithmic meaning a 1 point change up or down is equal to a tenfold increase in acidity/alkalinity.

Home/Office Water Softeners:
Finally, home (or office) water softeners that employ salt should NOT be used for supplying aquarium water, as these strip most important minerals all the while increasing sodium to very high and out of balance levels (sodium is only required in trace amounts for most fish), this can severely affect osmoregulation in fish, especially many fish such as Loaches that normally prefer more soft water, but not soft water containing an unbalanced mineral content that is high in sodium but missing other essential mineral ions.

Products that can aid in re-mineralizing RO water (many can be/should be used with other products for complete re-mineralization that includes carbonates)

*Wonder Shells (an important compliment or even stand mineral replenisher; mixes well with Electro Right, Replenish, RO Right, SeaChem Buffer)
*SeaChem Replenish
*Kent RO Right
*SeaChem Marine Buffer (for balanced carbonate/bicarbonates for correct KH & pH)
*SeaChem Cichlid Salt (similar to SeaChem Buffer along with added sodium chloride salts)
*Aquarium Pharmaceuticals Electro Right

These products can be used separately or together. The API ElectroRight only adds important trace minerals and no carbonates and is usually inadequate by itself. I generally would soak a Wonder Shell in RO water and then add Buffer or Cichlid or Marine Salt to further replenish major and minor elements as well as carbonates (which Wonders Shells have little carbonates).

Necessary Minerals

Here are a few necessary TRACE elements/minerals (electrolytes) and their function. Please read the above article for more about Calcium.

• Calcium (Actually needed in more than trace amounts): Calcium helps to transport ions (electrically charged particles) across the membrane, is essential for muscle contraction, calcium assists in maintaining all cells and connective tissues in the body, and much more
• Sodium (Actually needed in more than trace amounts which is why water from home water softeners should NOT be used): Regulates extra-cellular electrolyte, essential for the transport of nutrients across the cell membranes.
• Potassium: Regulates intracellular osmotic pressure, cell membrane potential, and salt excretion.
• Phosphorus: Energy metabolism.
• Molybdenum: Important for proper skeletal growth (very important in reef aquariums for hard coral growth).
• Manganese: Aids enzymes involved in metabolism, growth and maintenance of bone and cartilage.
• Iron: Oxygen transport in blood and muscle tissue.
• Magnesium: As stated previously, magnesium plays a role in the activity of more than 325 enzymes and aids in the proper assimilation of Calcium.
• Sulfates: Also as stated above, improve nutrient absorption and toxin elimination.
• Chromium: Important for proper utilization of sugars.
• Cobalt: Necessary for Folic Acid synthesis.
• Copper (very trace amounts): Co-enzyme for energy metabolism, aids in the protection of the myelin sheath around the nerves, important for iron absorption and utilization.

For a related post that deals with trace elements:
“Plaster in Paris in Aquariums and Ponds”


It is important to have a proper Redox Potential which describes the ability for the loss of an electron by a molecule, atom or ion to the gain of an electron by another molecule, atom or ion. Without this reducing Redox Potential many minerals cannot be absorbed and properly assimilated. So it is very important to keep a “positively charged” aquarium or a Redox Potential of approximately -300 mV via proper dissolved oxygen levels, calcium and other electrolytes, proper cleaning procedures and water changes (UV Sterilization can help too).
Redox is NOT a water parameter the average aquarist needs to worry about, as good aquatic husbandry usually takes care of this however it is still a useful parameter to be familiar with.
For more information about the Redox Potential, please see my article: The Redox Potential in Aquariums (& Ponds) and how it relates to proper aquatic health

For Wonder Shells which aid in the addition of electrolytes (an excellent product I have used for years with very good results as a tool for maintaining proper water parameters): “Wonder Shells” -for calcium and electrolytes

For further reading on this subject, here are a few articles I recommend:

This one is great
Understanding Water Hardness

A little hard to follow (pdf), but good reading:
Interactions of pH, Carbon Dioxide, Alkalinity and Hardness in Fish Ponds

This article is a very interesting (although somewhat dated), especially as it pertains to the benfits of lower salinity for Marine teleost/teleostei fish (ray-finned fishes):
Osmoregulation (http://www2.hawaii.edu/~delbeek/delb11.html)
This point from this article is noteworthy:
"Since marine fish must constantly expel various solutes,
such as sodium and chloride ions, against an osmotic gradient, a
great deal of energy is required. Therefore, anything that you can do
to lower the osmotic gradient will benefit the fish in terms of
energy expenditure. The simplest way of doing this is to lower the
salinity of the water as much as possible, particularly for a fish in
distress."

For more aquarium information, please visit this site: “AQUARIUM AND POND INFORMATION”

For a VERY knowledgeable aquatics forum with a lot of aquatic experience:
Everything Aquatic

Other Resources:
Sodium Ions: http://www.elmhurst.edu/~chm/vchembook/142Aposion.html

Copyright Carl Strohmeyer 12/04/06