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Aquarium Substrate, Gravel, Pebbles & Sand; Which to Use?

Aquarium Gravel/Sand Substrate, Which to Use; Including Pictures


For the average fish only freshwater aquarium I recommend 2-3” of #3 gravel (#3 gravel is .2 to .5 cm in size) or a larger pea sized gravel #5. (#5 is generally about 1 cm)
This allows less build up of hydrogen sulfide producing anaerobic bacteria than with sand. The down side to larger gravel is that it will allow for more waste particle or eaten food to accumulate in the larger crevices that form between the pebbles. With proper cleaning procedures though, waste accumulation should not be a major problem.

*Sunburst Rock; #3 Gravel
*Sunburst Rock; Pea sized gravel (#5)

Unless the gravel/sand is labeled as "pre-rinsed", it should be rinsed in a bucket about three times (or until it runs clear).

If you are not planning to add plants, I would be careful with the use of #00 or #1 sand (#1 sand is commonly used in mortar/masonry) as this can cause dangerous anaerobic Hydrogen Sulfide production in un-planted tanks when anaerobic de-nitrification goes from production of nitrogen to hydrogen sulfides due to sulfur reduction; please see this article for more on this subject:

Hydrogen Sulfide production in anaerobic De-Nitrification for Aquarium/Pond Nitrate Removal

If #1 sand is used in a non-live planted freshwater aquarium, the use of #3 or #5 also provides a way to lower your chances of hydrogen sulfide production. Larger debris/organic mulm will gather for easier cleaning with a gravel vacuum, or Eheim Sludge Remover.

Sand is good for heavily planted aquariums. It provides a better anchor for the roots and even more important, it traps nutrients and symbiotic bacteria needed by plant roots. If used for live plants, I recommend about ½” #00 or #1 sand followed by 2-1/2” of medium (#3) gravel, with laterite mixed in around plant roots. Be careful when vacuuming sand as it is easy to suck it into the vacuum and if it is a powered vacuum, this can damage it or clog a Python or similar.
I recommend quick probes into sand and possibly ‘kinking’ the tubing behind the vacuum nozzle to allow the sand to settle back into the tank.

If your aquarium is going to be only lightly or moderately planted, I recommend sand only in the area around the plant roots and use #3 size gravel (or larger) elsewhere.
Sometimes in these lightly planted aquariums I will actually substitute sand for lightly sifted sandy soil.
I prepare this by digging in a clean area for my soil then I rinse it gently (as if I am panning for gold). After I have rinsed out the muck and dirt I add a 20/1 water/bleach solution for a few minutes then rinse it with a De-Chlorinator and I am ready to go.

A better method (that can be use to totally replace the aquarium substrate or used only around plant roots) are products such as Eco-Complete or SeaChem Flourite.
Flourite Aquarium Plant Substrate in particular will add iron, calcium, magnesium, potassium, sulfur and many other elements to nourish your aquatic plants. Unlike competing products Flourite may be mixed with other gravel and it never has to be replaced. It remains effective for the life of the aquarium.
Flourite is excellent when combined with Sea Chem Excel.

Product References:
SeaChem Flourite Plant Substrate
Sea Chem Excel


Colored/Epoxy Coated gravels have been quite popular in the past.
The epoxy coating can be used to just make natural gravels appear more shiny or as a way to bring a rainbow of colors to your aquarium substrate.

The downside to these epoxy coated gravels is that this coating in time can peal and allow for trapping of organic debris that will show up as higher nitrates, lower pH/KH, and a poor Redox balance. If this happens, it is best to change out your epoxy coated substrate,
Another downside is these epoxy coatings do not allow as much surface area for nitrifying bacteria, although this is in reality more of a problem when under gravel filters are employed.

Here are a few pictures of Aquarium Gravels I have used and recommend: (Please click pictures to enlarge)

Pea sized aquarium pebbles, substrate for goldfish Regular Pebbles- excellent pea sized (slightly larger than pea size) for use with Goldfish and Bettas

Coral sea Pea sized aquarium pebbles, substrate Coral Sea Pebbles- another good choice for Goldfish, Bettas and other larger pea sized gravel applications

Rainbow number 3 aquarium gravel, substrate #3 Aquarium Gravel, natural rainbow- excellent overall aquarium gravel for most freshwater applications

White coral number 3 aquarium gravel, substrate #3 Aquarium Gravel, White Coral- excellent overall aquarium gravel for most freshwater applications (this is NOT actual coral, rather natural rocks with the color of coral rock)

White coral number 3 aquarium gravel, substrate #1 Aquarium/River Sand- excellent for planted aquariums. This sand is best used only where plant roots are present and only to be used with other more coarse substrates in areas where plant roots are not present. Where roots are present, 100% usage is OK.
Use of #1 sand in areas that are not turned regularly or where plant roots are not present can result in Hydrogen Sulfide production in your aquarium

Hydrogen Sulfides in aquarium

I would recommend checking with local decorative rock/building supply business for these substrates, such as this Sun Burst Rock in Los Angeles County.


By Carl Strohmeyer American Aquarium Products-Aquarium Information

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In Chronological order of writing with the newest at the top

  1. How to Treat Sick Fish
  2. Whirling Disease in Fish
  3. Reef Aquarium Chemistry Maintenance
  4. Use of RO, DI, Softwater in Aquariums
  5. Lighting Theory of a Planted Aquarium- RQE, PFY, PAS, & PUR
  6. Aquarium or Pond Bio Load
  7. Tuberculosis in Fish
  8. PUR vs PAR in Aquarium Lighting
  9. Head Pressure in Aquarium and Pond Water Pumps
  10. Fin/Tail Rot For Betta & ALL Fish
  11. Angelfish Virus/Aids
  12. Activated Carbon
  13. Fish Baths/Dips as an aid to treatment
  14. Streptococcus gram positive bacterium in aquariums, Eye Infections
  15. Hydrogen Sulfide
    production in anaerobic De-Nitrification for Aquarium/Ponds
  16. Fish Shipping
  17. Aquarium Size, Fish Stunting
  18. Aquarium Algae,
    BBA & Brown Algae in particular
  19. Aquarium Salt (Sodium chloride) in Freshwater Aquariums
  20. Betta Habitat; Wild Bettas to Domestic Betta environment parameters
  21. HITH; Hole in the Head Disease
  22. Aquarium Protein Skimmers, Ozonizers
  23. Power Head/ Water Pump Review
  24. Molly Disease/ Mollies in an Aquarium
  25. Basic Fish Anatomy, Fin Identification
  26. Aquarium Moving/ Power Failures
  27. Octopus as Aquarium Pets
  28. Aquarium Nitrates
  29. Ichthyophonus protists, fungus in fish
  30. Aquarium and Pond Filter Media
    Types; Mechanical, Bio, Chemical
  31. Aquarium Water Conditioners (also Pond)
  32. Fish Parasites; Trematodes & Monogeneans; Annelids and Nematodes;
    Flukes, internal worms, Detritus Worms (often confused with Planaria), Micro Worms
  33. Aquarium Silicone Application;
    DIY Aquarium Repair & Glass thickness
  34. Pond Veggie Filters; DIY Bog Filter
  35. The difference between Plaster of Paris and Aquarium Products such a Wonder Shells:
    Identification, prevention & Treatment
  37. AQUARIUM TEST KITS; Use & Importance
  38. SEXING FISH; Basics
  39. Chocolate Chip, Knobby and Fromia Starfish
  40. Freshwater Velvet & Costia
  41. Usnic Acid as a Fish Remedy
  42. Aquarium Heaters; Types, information
  43. The Lateral Line in Fish, Lateral Line Disease
    or Head and Lateral Line Erosion (HLLE)
  44. Tap Water use in Aquarium; Chloramines, Chlorine
  45. Can Black Ghost Knife fish give an electric shock?
  46. Bio Wheel Review; Do Bio-Wheels really work?
  47. How do Fish Drink?
    Use of RO Water
  48. Cyclops, and Predatory Damselfly larvae
  49. Betta with Dropsy;
    Treatment and Prevention of DROPSY in all fish
  50. pH and KH problems in African Cichlid Aquarium
  51. Aquarium Gravel, which size?
  52. Blue green algae, Cyanobacteria in Ponds/Aquariums

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