Monday, April 30, 2007

Substrates for the Planted Aquarium

Choosing the right substrate for your planted aquarium is an important decision that will have long term affects on your plants. Although the impacts may not be as immediately visible as say lighting or CO2 choices, the substrate in your planted aquarium is a critical part of your aquarium's ecosystem and vital to the health of your plants. There are many different options, all of which have benefits and drawbacks, but I'll highlight some of the most popular options. Overall, there are a few basic requirements that must be met to be appropriate for a planted aquarium:

  • A planted aquarium substrate should not be too large or too small (usually between 3-8mm per grain). This is to accommodate root growth; grains that are too small will suffocate and crush roots while large grains won't provide enough contact with the roots.
  • A planted aquarium substrate should not affect the water chemistry negatively. Many substrates are designed for other uses, including salt water use, and may leech minerals and salts into the water. For example, crushed coral leeches calcium into the water of an aquarium. This can raise the pH and KH (carbonate hardness) in a freshwater planted aquarium to damaging levels. Substrates that maintain a constant pH level may also be undesirable, as different plants thrive under different conditions, and changing a substrate is probably one of the most difficult procedures to complete in an established aquarium.

The most valuable input and feedback on popular planted substrate brands comes from hobbyists themselves, and much of this information has been taken from planted aquarium forums. Therefore, you'll get much more information than just what it says on the label. If you have a chance, do a search for planted aquarium substrate or one of the following brands on a planted aquarium forum, such as Aquatic Plant Central. Just remember to take what you find with a grain of salt, as these are often extremely un-scientific reviews.

Planted Aquarium Specific Substrates

$20-25 for a 20lb. bag

One of the top planted aquarium substrates today, Eco-Complete is a balanced, easy to use substrate. It comes populated with beneficial bacteria, so if you are starting a new tank, you can jump-start the cycling process. It also doesn't require rinsing, which is a big pain to have to do, and an even bigger pain later if you don't do it! It comes packed with essential nutrients and minerals required for live plants and shouldn't impact your water parameters (Unless you bought a really old bag, as they did have a few quality problems about a year ago. These can be identified by milky white liquid in the bag, but they will replace the bag for free). The grain sizes are within range for optimal root growth and the appearance is of a deep black sandy gravel. It's also rounded gravel, and poses no threat to bottom feeding fish which may hurt themselves on sharp edged substrate. I use Eco-Complete almost exclusively, and for the price, you can't buy a better substrate in my opinion!

$15-20 for a 15lb. bag

Flourite has been around for a while and is not as technologically advanced as other substrates available now but is still an old stand by. It is a clay based substrate with a reddish color that comes from its high iron content. The major drawback with Flourite is that is needs to be rinsed extensively before putting it in the aquarium, otherwise it will severely cloud up the water. It's also larger than other planted substrates and may pose a problem for plants with small, delicate roots. It doesn't have as much or as many minerals and nutrients as other planted aquariums substrates available today. However, you can't really go wrong with Flourite: it's tried and true.

ADA Aquasoil
$26 for a normal type 9L bag (roughly equivalent to a 15lb bag) from ADG

Supposedly the best planted substrate money can buy, Aquasoil is researched and manufactured by Takashi Amano's Japanese company, ADA. There are several different varieties, based on biotopes from around the world. These range from Amazonia to Malaya and Africana, all with different colors and properties to simulate the biotope for which they are named. Made up of round grains, the substrate maintains gaps allowing for water circulation to prevent roots from suffocating, although now they also sell a powdered version to make the top level of the substrate more attractive. It's engineered to lower the pH and general hardness (GH) of the water (this effect is not to be confused with the lowering of pH associated with adding CO2; simply lowering the pH using Aquasoil is not adding any CO2!). Most plants grow better at a lower pH of about 5.5-6.5. If that weren't enough, Aquasoil also acts as a passive filter, capturing floating particles. Nobody knows exactly what it's made of, but it maintains its shape long-term and provides nutrients for root feeders. I haven't been feeling wild enough to start a tank with Aquasoil yet (even though the price is now quite competitive) but others who have swear by it. If you don't have a large tank, or like knowing you bought the best money can buy, Aquasoil is for you.


Diana Walstad's book, Ecology of the Planted Aquarium, is your bible for using regular potting soil. Most people who use soil are following her methods to create a "el Natural" style aquarium. The benefits of this style is that it requires very little maintenance or fertilizing. However, using soil submerged can be very challenging and there are many ways to do it wrong, leading to certain disaster. Like in nature, a soil substrate does grow plants very well. If you plan to use soil, definitely read her book or ask around on planted aquarium forums for advice!

Traditional Substrates

Regular Inert Gravel
$10-15 for a 20lb bag

Believe it or not, regular intert gravel can also be used quite successfully as a planted aquarium substrate. More intensive fertilization will have to be done to maintain more demanding plants, but it is possible. If going this route, try to get smaller gravel as most gravel sold will be large and difficult to root small delicate plants and stem plants with shallow roots. If you already have an established aquarium with gravel, this is ideal, as the fish mulm has already accumulated in the gravel and will act as a fertilizer. If you are starting from scratch, root tabs or other substrate fertilizers can be used to give plants a boost until the mulm builds up.

$5 for 20lbs or less

Sand must be used with caution as a planted aquarium substrate. It is very attractive, but has many downsides. First, it tends to compact, making it very difficult for roots to grow into it. Secondly, this compacting can lead to reduced circulation and pockets of anaerobic (not requiring oxygen) bacteria thriving, creating toxic gas bubbles. To prevent this, it's best to either layer one of the other planted aquarium substrates underneath the sand or use a very large grain sand. Overall, sand is best reserved for an accent area, creating a sandy beach effect, and is not ideal for growing plants.

Substrates to Avoid

Red Sea FloraBase

I almost bought this planted aquarium substrate as it was attractive and not too expensive. However, I looked up other's thoughts online and found out that although it is a great planted aquarium substrate for the first year or so, it requires replacing (it even says so on the label). Otherwise the granules, shaped similarly to ADA Aquasoil granules, will begin to lose their shape and "melt" into mush. This can be disastrous. Coupled with the fact that changing the substrate in an established tank is all but impossible without totally destroying it, this planted aquarium substrate is one to avoid unless you tear down your aquariums every year.

Laterite (Cat Litter)

This is not really a substrate but more of an additive to substrate. It is a form of clay that contains iron and acts as a sponge to store nutrients, but is meant to be mixed into the existing substrate (usually inert gravel). However, it is clay, and thus gradually softens into a mud-like substance that if disturbed, will cloud your tank dramatically. If, like me, you move plants around frequently, this can mean a cloudy tank all the time.

So these are the top planted aquarium substrates and those to avoid as a planted aquarium substrate. There are many more options, but these are less common and more experimental. You can find an infinite number of combinations of materials and their performances on planted aquarium forums. As for substrate depth, 2-3 inches is generally the rule of thumb. Shallower than that will lead to problems with roots not being able to go deep enough and it will be hard to anchor plants. Much deeper...well why would you make it much deeper? You're keeping a fish tank, not an ant farm! Good luck!


  1. Great post! I actually just set up a new 10 gallon tank tonight with some eco complete as I had a blast using it in my 29G. I haven't looked into the ADA stuff as the ecocomplete has the look and nutrition for my plants that I've needed so far.

    Keep up the good work! Your blog is one of my favorites.

  2. I disagree on the sand issue, I find that aquariums that use sand require significantly less substrate depth than aquariums that don't (I have had 2 30"+ swords growing in about half an inch of sand for 2 years. They bloom annually and send flower spikes to the ceiling). I also find that one of the tricks to sand as a substrate is the use of fish and inverts to keep it aerated. My favorite is horse faced loaches. as they do an excellent job keeping the sand aerated. Trumpet snails, coolie loaches, and larger corydoras work well too. The best aerators are dojo / weather loaches but they are too big for most plants and uproot them constantly.

  3. Amazing post! Good work! I had your blog in my favorites.


    Luís Moniz

  4. Hello! I'm a hobbyist from Singapore, and enjoy reading your blog. Hope you don't mind if I link you!

  5. Thanks so much for this entry. Armando and I have just made a mistake in buying black colored gravel. We wanted a darker substrate but the black gravel was painted and we were very annoyed and threw it away after we saw that the water was turning black after several washings of the gravel. We hope you don't mind, we made an entry on our blog

    and linked to your substrate entry. Really great information and helpful! We are about to set up our 55 gallon aquarium.

    I will visit again and thanks again for the helpful entry!


  6. Great post with great information.

    Would just like to add some extra information about the gravel Flourite. Although it is a decent plant gravel, I would just like to emphasize the drawback you already mentioned; the cleaning. It is extremely frustrating and takes many many hours to get it to a usable clean state. The first plant gravel I purchased, I rinsed and cleaned and was shocked at the pitch black color the gravel produced. After an hour of so, I thought I had cleaned it enough and put it in the aquarium with the water. Imagine my surpise when I saw the water was just as dark. Frustrated, I emptied out the water and took the gravel outside and cleaned it further. It took hours and hours with multiple strainers and hoses. Finally, I put it back in the aquarium, and to my much dismay, was still slightly muddy. Further more, the slightest disruption of the gravel(siphoning, etc.) would send a cloud of blackness up into the water. Finally, I emptied it out and took the gravel out and bleached it(A horrible mistake, but I was a novice). It did get rid of the problem, but caused many more, so I suggest not doing it. Anyway, point is try not to get Flourite( I know that major retailers such as Petco and Petsmart only carry this brand of plant gravel, but go elsewhere) and save yourself much frustration and time.

  7. I have noticed some plant loving aquarists use a clay loam soil rich in trace elements beneath a shallow layer of typical aquarium gravel. Wouldn't this create an anarobic environment in the substrate with high concentrations of hydrogen sulphides in solution of which are harmful to fish? I have used Dupla laterite in my tank set up with conventional sand (grain size 1-2mm) and my plants loved it for the first four weeks and then I was starting to get yellowing of the leaves on some of the plants. My Java fern is now all black and wasting. I now have have CO2 injection but seem to be still getting the yellowing (albiet less severe) even though I have been adding clay balls beneath each plant. Trace elements are also goin into the tank each day too. Does anyone have an idea what Im doing wrong? Too much or too little, something missing??? mmmmmmm

    1. In addition to hydrogen sulphide anaerobic denitrifying bacteria can develop within the oxygen depleted parts of the soil. Being a bacteria it takes time to colonize (explaining the four weeks delay) these places and effectively remove nitrates from the soil. This could be great if it weren`t next to any plant roots (where plants usually prefer to take in nutrients). Even a very small degree of water movement through the soil can stop this problem... a thinner layer of soil and/or a larger grain size might do the trick. I`m sorry you already have it set up though. :/

  8. I have Florabase mixed with a small gravel in both my 29 gallon, and ten gallon, and so far have noticed that the tank clouds easily when the substrate is disturbed, and the filter clogs on my over the back filter very quickly. However, the corydoras in my 29 gallon couldn't be happier. They can root around, and dig for foodstuffs that collect in the substrate. I've had the tanks set up now for a while, but don't look forward to breaking the tank down in the future to replace the florabase currently in it. A suggestion on removing the substrate would be to gravel vacuum out the substrate until the tank is bare when needed, and to slowly add new substrate to reduce clouding. I know in heavily planted aquaria this may be out of the question, but it may be better than removing everything, and starting over.

  9. Hi , Great Blog.

    My expeirience with Flora base -

    Ive been using flora base in my tanks for a while now with good results. Personaly I do not feel the yearly change is an issue as most of the aquascapes I try to achieve have long since past their peak by this time (grown out). Does ADA aquasoil or ECO complete have an unlimited suppy of nutrient? does the exhaustion rate not depend on how heavily planted the aquarium is and which plant species are used? If the issue is simply that of the substrate breaking down or compacting I can honestly say ive seen no evidence of this after 18 months use, however I do not keep Corydoras catfish of other gravel shifting species. I may be tempted to use ECO complete in my next tank as it is so highly favoured but im in no hurry to remove the Flora base despite the manufacturers recommendation. I currently have a healthy lush green carpet of HC growing im my old Flora base.

    Just my opinion!

  10. Hi,

    I hope I don't sound too silly.

    I have a 24 gallon tank and have never had live plants. I would like to start some. My question is it too late to add a substrate. My tank is established but the gravel I have on the bottom is too large I think for plants. I was thinking of have two 'zones' in the tank, one half leave the gravel that is in there, and on the other half add a better substrate and plant it. Am I crazy?

    Any thoughts or help would be appreciated.

    thanks for the consideration.

  11. anyone, please help me...

    i'm thinking to use Aqua Soil from ADA. do i need the Power Sand and substrate additives (both from ADA)as well? coz they both are very expensive.

    please email me:

    heaps thanx

  12. I'm about to start a new 20 gal with 110-130 watt compact fluorescent lighting, an eheim 2213 filter and DIY CO2 with a glass diffuser. The only thing I have left to decide upon is the substrate--I've never used true plant substrate before, just small-grain gravel. I'm stuck between buying eco-complete and splurging on ADA soil and I was wondering if you've had a chance to experiment any further with the ADA soil?

    My local shop owner uses the ADA substrate in his amano style tanks and seems to like it a lot. Do you (or anyone else) have an opinion on this yet?



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