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Aquarium Protein Skimmers, Ozone Generators; Review
Marine (Saltwater) Aquarium Protein Skimmers; Review
- Basics (Overview)
- Types of skimmers;
- Air driven
- Venturi (such as TMC V2 Skim)
- Aspirating/ Needle Wheel (Such as ASM)
- Spray Injection (such as Remora)
- Basic Economy Skimmer
- Use of Ozone Generators
By Carl Strohmeyer
Information and opinions here are not only based on my experience in the Aquarium Maintenance business (over 30 years) but also of colleagues in the “higher end” aquarium maintenance and design business.
Marine Protein Skimmers are a fast growing technology area of aquarium keeping, as is aquarium lighting, UV Sterilization, Redox, etc.
What may be true today may not be a year from now.
20 years ago I often found the benefits of finicky and unreliable protein skimmers not worth the trouble for the payoff in results when compared to other filtration methods, especially since I could only visit a client once per week.
However, as of the last decade I have to admit a reversal of opinion, and this is based on the much improved protein skimmers of today that are much more reliable and effective and are worth the expense and any extra hassles.
This said, based on emails, question, and discussions with colleagues; these are NOT a beginner piece of aquarium equipment in most instances or at least with the better skimmers such as the ASM or TMC V2.
What I mean is that many of the better Protein Skimmers take some DIY abilities as well as understandings of the principles upon how these devices work such as a venturi.
However I have had discussions with many whereby the consumer cannot seem to ever get their skimmer to work correctly, often resulting in these persons being critical of the device when it was not the device at all upon inspection of the so-called problem/suspect device.
A protein skimmer is a filtration device which employ a chamber with a column of fine bubbles.
Protein Skimmers are used primarily in marine tanks.
They do not work as readily in freshwater, although there are pond models.
Protein skimming works by a process called adsorption (not to be confused with absorption) which is the attraction of DOC (Dissolved Organic Compounds) onto a suitable surface.
The process takes advantage of the physical nature of DOC (protein based) molecules.
Surface tension attracts organic waste to the bubbles & carries it through the column (called foam fractionation); it is then "skimmed" into a collection cup, where it is then emptied either by hand or a drain (depending on the model).
This process removes nitrogenous waste (protein based organic waste) and is also called "foam refraction".
Protein Skimmers come in pump driven and air driven models. Within the pump driven there are different types: Venturi, Aspirating, Downdraft, and Spray Injection; the first two being most common.
Protein skimmers are often needed to keep nitrates well below .20 ppm for the delicate marine invertebrates such as Acropora Corals.
The advantages of protein skimmers are that they remove nitrogenous waste before they can go through the nitrogen cycle and become nitrates.
The disadvantages are some are messy and can often take frequent adjustments.
I have kept many reef aquariums successfully with and without protein skimmers although I do recommend them for reef aquariums, especially with the much better skimmers now available.
What I personally find interesting, is that many of the aquarists that swear by protein skimmers totally trash UV Sterilizers, yet I have found from experience over the years that often UV sterilizers had more positive attributes than the older protein skimmers (I would not apply this analogy to the high end modern skimmers).
That said, a good Protein skimmer is even better when used in conjunction with the Berlin Filter Method for reef aquaria and should be considered, more so if you are planning on keeping delicate corals.
Further Reference: UV Sterilization; Aquarium UV Sterilizer Use
The co-current air driven models (also called columnar skimmers) are the most basic, although not always the simplest to use as these cheap Skimmers are often temperamental to water levels in the tank and the limewood air stones used by these skimmers clog frequently. These can however, be an inexpensive entry level Skimmer for 10 -60 gallon marine aquariums.
Personally I find these skimmers can be more trouble than they are worth, so I would strongly recommend one of the higher end skimmers recommended further in this article.
This type of Skimmer is ozone compatible, but this can be difficult to control with these air driven Skimmers (Ozone works best with Venturi Skimmers)
Where to purchase: Wooden Air Stones for Protein Skimmers
Of the pump driven Skimmers, the co-current Venturi models are the most common and popular.
This style uses a water venturi pump. This is sometimes referred to as an aspirator. The Venturi pushes tank water into the pump which is used to introduce fine bubbles of the correct size and number into the skimmer body.
This Venturi can be used on the air suction side to attach an Ozone Generator for improved Skimmer efficiency (no air pump required for Ozonizer/Ozone Generator use).
The Venturi Skimmer design lends itself to basic low end protein skimmers, that although certainly are not the best, these will still allow for reasonable protein skimming for a lower price. However the higher end Venturi Skimmers, such as the V2, will far surpass the lower end venturi skimmers (such as a Rio Nano Skimmer), due to much better time, bubble exposure time in the current, and its bubble stop that allows for bubble recycling.
As well, not all higher end venturi skimmers are equal, some of the more basic designs such as the Bak Pak work well, but the newer designs such as the V2 Skim by Tropic Marine also has a patented Bubble Stop in which the skimmer is fed 'dirty' water from the aquarium as a means to re-circulate water within the skimmer multiple times before it is returned to the sump or the aquarium.
As previously noted, the Tropic Marine V2 Skim is one of the better ones with the latest in venturi skimmer technology. This skimmer has a venturi injection system which optimizes the perfect mixture of fine air bubbles and water and ensures intensive, efficient skimming and the removal of proteins and other harmful toxins (waste) from the aquarium. This Skimmer also has a Bubble stop feature that essentially re-skims the water as well as prevents bubbles/foam from re-entering the aquarium.
Each time water is re-circulated within the skimmer any air bubbles in that water sample are destroyed and new bubbles are generated by the re-circulating pump venturi apparatus so the air-water contact time begins again for these newly created bubbles.
For the money, the V2 Skim is the best Protein Skimmer you can buy unless you are willing to spend more money for the even more advanced mesh wheel skimmers such as the Warner Marine, ASM skimmer, or similar for what is often a more temperamental skimmer.
Since the TMC is ozone compatible (via the air vacuum created by the venture), the addition of an Ozone Generator can make this a Protein Skimmer that is “second to none” (at any price).
Where to Purchase:
*TMC V2 Skim, Premium Venturi Recirculating Protein Skimmer
*TMC New Technology Ozone Generators
Aspirating; Needle Wheel/ Mesh Wheel
An aspirating or mesh wheel Protein Skimmer generally uses an impeller which consists of a mesh material that is attached to a plate or central axis on the rotor.
The purpose of these modified impellers is to chop the air that is introduced via a venturi apparatus or external air pump into large amounts of very fine bubbles. Because of this, generally an air pump is required for Ozone Generator use
A claimed advantage of this style is, when done correctly, is that these skimmers generally have a larger neck size that allow for less clogging of bubbles/foam. This is due to generally higher bubble production that allow for a wider neck.
My personal opinion, and that of many others in the business, is that one should be cleaning the neck each time one empties the foam cup as the cup generally fills in most skimmers long before this becomes a real issue.
This style is used in by many companies such as Coralife. However I do not recommend the Coralife model.
This style is gaining popularity; however it still has some bugs in that not all of the impellers used by these always chop the air bubbles properly due to anomalies in the flow, and impeller design that can result in pump burn up.
The ASM Protein Skimmer is one of skimmers in this category that I can recommend based on the high end marine aquarists that use it.
What differentiates this aspirating skimmer from the rest is that it has a unique "custom" impeller housed in the specifically modified Power Head that chops the bubbles very finely.
Another aspect of this aspirating skimmer is that it combines a venturi with its custom meshing needle wheel pump. The negative to the ASM Protein Skimmers is the price, as these units will retail for many $100s of dollars. I will also add that I have been told that this skimmer has some issues with the mesh wheel pump, although this has not been confirmed by others in the aquarium maintenance and design business.
Other skimmers in this category include the Warner Marine Skimmer and the Via Aqua Needle Wheel Protein Skimmer.
I currently do not have much feedback from reliable resources on either of these skimmers (although the Warner Marine does come from one trusted source).
The Via Aqua Needle Wheel appears to have a good design and my experience with 80% of their products is usually good, especially for the price.
(Pictures can be clicked to enlarge)
A downdraft protein skimmer injects water under high pressure into tubes that have a foam or bubble generating mechanism. It then carries the air/water mixture down into the skimmer and into a separate chamber.
This design is generally used in large aquarium systems and uses tubes with plastic media (often bio balls) inside to mix water under high pressure and air in the body of the skimmer resulting in foam that collects protein waste into a large collection cup.
The Spray injection skimmer, such as the Remora, are a take off from the Downdraft Skimmers.
These use a pump to power a spray nozzle, set a few inches above the water level. The spray action entrap and shred the air into very fine bubbles in the base of the unit, which then rise to the collection chamber.
The Spray Injection Skimmer is a fancy new name for the Downdraft style Skimmers which work well in the large industrial size environment in which they were originally designed for, however this design does not lend itself to small sizes well.
This style skimmer can clog with time, is sensitive to water levels, tends to produce a watery muck (instead of foam), and can be temperamental when used in a sump environment.
These skimmers are really being hyped and over promoted by many (often the usual suspects). However I and MOST aquarium professionals, would recommend steering clear of these units.
Although the Remora can work, results are often poor, and the design is flawed.
For the same price a TMC V2 Skim will far out perform the Remora (especially with an added Ozone generator) and for far less money you could probably do just about as well with a Rio Nano Skimmer especially when combined with "NPX Bioplastics Nitrate & Phosphate Reducing Polymer Media" and with SeaChem Matrix added to bio filters.
Where to Purchase:
*NPX Bioplastics Nitrate & Phosphate Reducing Polymer Media
*SeaChem Matrix; Nitrate Remover Bio Filter Media
Basic Skimmers, (Skimmer filter combinations)
A couple of basic skimmers for beginners; Via Aqua Multi Skimmer with small to medium aquariums is relatively simple, with a mechanical filter cartridge, bio filtration ability, and most of all the Multi Filter has a built in UV Sterilizer combination.
For a really simple protein skimmer for a Nano tank I recommend the Rio Nano Skimmer.
Where to Purchase: *Rio Nano Skimmer, HOB Filter
Use of Ozone Generators
As noted earlier in this article, an Ozone Generator can greatly improve efficiency as it enhances flocculation and absorption onto the bubble wall of an air driven or venturi style Protein Skimmer.
As well, the Ozone Generator can also lower many pathogen (such as bacteria and viruses) in the water column, similar and as a compliment to a UV Sterilizer.
The exact increase of efficiency by adding an Ozonizer has not been established by any controlled test that either I have performed or read.
However what is clear (based mostly on observations) is that the amount of waste collected can increase dramatically, especially in skimmers with less than perfect exposure time of fine bubbles in the water column of the skimmer.
As observations have also shown that the addition of an Ozone Generator to a Skimmer will clear a cloudy aquarium at a faster rate than a skimmer without an Ozonizer.
As well, the use of an Ozone Generator allows for less than perfect bubble sizes to still perform reasonable adsorption (the attraction of DOC onto a suitable surface), thus allowing for less efficient skimmers or the use of many skimmers in freshwater ponds or aquariums where the skimmer would otherwise likely produce little waste foam.
HOWEVER it is also noteworthy that while an Ozonizer does perform sterilization, often at lower costs per watt of energy than a UV Sterilizer, these devices are still only a compliment to a UV Sterilizer.
WHY? Because an Ozonizer does not destroy destructive oxidizers and aids in establishing the proper balance of electromagnetism of the water column which can otherwise add oxidative stress to fish as does a UV Sterilizer.
Together an Ozone Generator and UV Sterilizer can improve both sides of the Redox Equation, but alone an Ozone Generator (Ozonizer), especially when used separate from a Protein Skimmer can actually increase oxidative stress.
Please Reference: Aquarium Redox Balance
Protein Skimmer Troubleshooting
- Collection Cup filling with water:
- Water level too high in skimmer, adjust skimmer upward in sump, tank, or in HOB applications
- Check water outlet (or water outlet valve if your Skimmer is so equipped); make sure there is proper flow.
- Check bubbles; make sure you have adequate fine mist bubbles.
- For air driven Protein Skimmers make sure you can blow through the wooden air stone relatively easily, otherwise replace. Check the air pump as well.
- For Venturi Skimmers, make sure your venturi is adjusted properly, with the air intake facing outward in some protein skimmers when inserted into the pump exhaust nozzle. Make sure that the pump itself is properly drawing and expelling water.
- For Needle Wheel, check pump flow as with the venturi, as well check the impeller that “chops” the air bubbles for damage or impediments.
- No foam in the Collection Cup
- This is normal for a new skimmer set up. The proper dry foam that is needed to collect the protein in the salt water, will take approximately 12 to 34 hours to start skimming. In new tanks, with little or no bio load, this may even take a few weeks.
- If there is adequate bio load and salinity, you may have to make very minor adjustments in skimmer height, relative to water level and make adjustments to venturi inlet. These adjustments need to be very minute, often Protein Skimmers require patience and constant adjustments, especially the more basic models.
- If powerhead driving a Venturi protein skimmer is too deep in the water, an insufficient amount of fine bubbles will be generated. The powerhead should be as close to the surface as possible, as increased depth will affect the ability of the Venturi to draw in air, reducing the skimming efficiency.
- A good counter current is important as well, as this is in part how Protein skimmers work. They use a fine mist of bubbles against a counter current of water. The larger the reaction chamber for bubbles to interact with the counter current, the better your dry foam production, which is why I do NOT recommend the unfortunately popular Spray Inject Skimmers that are over priced for what you get.
- Bubbles are escaping the Skimmer into the tank
- Often this is caused by chemicals that have been added which result in increased surface tension of the water. Stress coats, de-chlorinators, medications, and water conditioners (which are present in most synthetic salt mixes) are just some of the additives that will cause this to happen.
Carbon will help to remove the compounds that cause this problem, as well many of the better high end Protein Skimmers have “Bubble Stops” to prevent this and recycle these bubbles such as the Tropic Marin V2 Skimmers
Here are some important aspects to consider to a purchase a skimmer that performs correctly:
- Contact time of bubbles and water inside the chamber (the longer the reaction chamber, the better in most cases)
- The size and consistency of the bubbles produced (very fine bubbles are best)
- The relative volume of bubbles produced
- The ratio of air to water
- The turbulence or friction inside the reaction chamber which may cause poor efficiency in some poorly designed units.
- The neck size is important as well, a smaller neck (which is to allow for lower bubble production), can clog easier and may need to be cleaned more frequently.
- The addition of Ozone can greatly increase efficiency of an ozone compatible protein skimmer such as venturi or air driven model
Please beware of claims of some high priced skimmers such as Spray Injection models as these units do not have the contact time (due to short/small reaction chamber) to maximize protein refraction.
Although units such as these do have excellent size and volume of bubbles, the small size of the reaction chamber minimizes effectiveness so that one of these units may perform better than similar size entry level skimmers such as the air driven Lee’s or the Rio Nano venturi skimmers. The price at nearly $200 is nowhere near the increase in effectiveness over a Rio Nano Skimmer (or similar) that costs under $30 as a price vs. increase in effectiveness comparison.
Finally, consider how much you can afford and your time as well. Obviously if you plan to keep SPS corals, I would consider a premium Protein skimmer a must, however even here, your time needs to be considered.
For example, the mesh/needle wheel skimmers tend to be on the cutting edge of marine protein skimming, HOWEVER the issues of pump burn out and the temperamental nature of these skimmers may make these a lesser choice for many. I personally still find the advanced venturi V2 Skim an excellent choice when these potential issues are considered, especially with the addition of an Ozone Generator
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