My thoughts on substrates and aquasoils

[Utar]

Take a look at these two pictures of my two tanks, one has a pea gravel cap for my aquasoil. The other has Black Diamond Blasting Sand cap for my aquasoil.
When it comes to fish poop, uneaten food, etc with a pea gravel cap, these unused nutrients have a path down and through the gravel to migrate down into the aquasoil below. But in the tank with the BDBS the unused said nutrients will just set on top and go nowhere, because this cap is so tight that there is no path to migrate down into the aquasoil below.





I am going to say something here that will make some of you kinda cringe, I have not vacuumed the substrate pea gravel since I setup this tank last June. The reason is there is not much substrate free surface area left to vacuum. The entire floor of this tank is covered with plants, wood, etc. I would have to take a bunch of the stuff out stressing out my fish, etc, etc and I don't want to have to do this. But as you can see even after five months the pea gravel still looks, good. The nitrate levels get a bit higher then I would like, but there are trade offs, so I do the water changes.

The new tank using BDBS, I will have to leave more room to vacuum, because the unused nutrients, uneaten food, etc will just set there and this is not good.

In the tank with pea gravel the unused nutrients will recharge the aquasoil below, but that is just my theory.

To close if I want a tank with less maintenance and not much need to vacuum that allows me to heavily plant then I will choose pea gravel over sand or BDBS.
If I choose to go with sand or BDBS, then I can only plant with a few plants like Amazon Swords, etc and not heavily plant, allowing the room needed to vacuum the substrate.

Please let me know what you think.

 

[ArmchairAquariest]

Yes my understanding with Sand is that you need things (tank critters) to mix it. Gravel is easier to vacuum without making a mess and lets things settle down if you have a dirt layer for plants. For sand you need things like:

-Malaysian Trumpet snails (which freely burrow in and out of it)

-a resident population of detritus and/or tubifex worms

-geophagus fish

-some big puffers will dig looking for snails.

-pea clams, a.k.a. fingernail clams, a.k.a. Pisidium [WHY ARE THESE SO HARD TO FIND FOR SALE? These are some of the best little maintenance crew support ever with some of the lightest bioload around and almost none of the problems that come with other freshwater clams.]

-Hyalella azteca, a.k.a. Scudds.

-Some Kulli Loaches

etc...

In the absence of any of those some catfish and shrimp help a little, but they only mix a relatively fine surface layer so they only help with a very narrow layer of sand. For a tank with none of these, then IMHO said tank is probably better off with pea gravel than sand for the reasons you have covered. With many of these "diggers" though they prefer a finer sand substrate over pea gravel to do their digging in, and in such cases they can keep your sand well mixed allowing poo and the like to settle down to a soil level if you have one.

 

[CassCats]

Certain substrates will limit stock options, since gravel is no good with many catfish or loaches. Not just to protect their whiskers, but also because they sift sand to search for food through their mouths and out their gills.

IMO sand is easier to keep clean and more flexible with stock, and is just fine for plants

 

[Wills]

What sort of aquasoil are you using? Most of the time you dont need to cap these unless its the base layer? I have Tropica Aquarium Soil in my high tech tank and its the easiest substrate I've had to get the waste organics off.

Going for sand in my next tank which is a lower energy set up - deciding if I want to have some sections with soil or put root tabs into the sand.

Wills

 

[mcordelia]

I also wonder if the flow inside the tank is affecting the "looks" of the pea gravel. You mention it is a heavily planted tank with relatively little free gravel surface area. that makes me wonder whether the current inside the tank pushes the detritus into a less visible place, keeping the gravel clean looking but resulting in detritus build up somewhere else. The most desirable situation would be that the flow would cause the detritus to travel all the way into the filter intake nozzle, but I fear that the more common scenarios may be that it gets washed behind an ornament or tangled inside plant structures. The latter is probably fine because your plants will happily likely use the nutrients, the former will eventually result in a big pile of rotting stuff somewhere in your tank that you have to find and get rid of somehow.

I had a tank way back when that had white gravel, and the gravel always looked pristine. However, after a while I learned to focus my cleanup efforts in certain corners of the tank, because it turned out that all the detritus was getting blown around and eventually ended up in a pile behind a specific rock.

 

[AbbeysDad]

What you're doing in the gravel tank is fine so long as you have lots of rooted plants to use the nutrients... Otherwise you have the potential for a nitrate factory unless gravel vacuuming is done. I have 3-4" of pool filter sand in my 60g and never touch the sand (well haven't in 8 years!) - the malaysian trumpet snails and a couple of cory cats do all the 'work'. - the beauty is nothing gets down under to rot and decay.
(see Aquarium Substrates)

 

[Utar]

Yes my understanding with Sand is that you need things (tank critters) to mix it. Gravel is easier to vacuum without making a mess and lets things settle down if you have a dirt layer for plants. For sand you need things like:

-Malaysian Trumpet snails (which freely burrow in and out of it)

-a resident population of detritus and/or tubifex worms

-geophagus fish

-some big puffers will dig looking for snails.

-pea clams, a.k.a. fingernail clams, a.k.a. Pisidium [WHY ARE THESE SO HARD TO FIND FOR SALE? These are some of the best little maintenance crew support ever with some of the lightest bioload around and almost none of the problems that come with other freshwater clams.]

-Hyalella azteca, a.k.a. Scudds.

-Some Kulli Loaches

etc...

In the absence of any of those some catfish and shrimp help a little, but they only mix a relatively fine surface layer so they only help with a very narrow layer of sand. For a tank with none of these, then IMHO said tank is probably better off with pea gravel than sand for the reasons you have covered. With many of these "diggers" though they prefer a finer sand substrate over pea gravel to do their digging in, and in such cases they can keep your sand well mixed allowing poo and the like to settle down to a soil level if you have one.

Thank you for this I had no idea about these clean up crews, I will make a list and start looking for them next time I go into the city. I have my own homemade aquasoil and it really needs a cap. For the most part made up of Organic Miracle Grow and Black Kow potting soils with extra ingredients added in for longevity.

 

[Utar]

What you're doing in the gravel tank is fine so long as you have lots of rooted plants to use the nutrients... Otherwise you have the potential for a nitrate factory unless gravel vacuuming is done. I have 3-4" of pool filter sand in my 60g and never touch the sand (well haven't in 8 years!) - the malaysian trumpet snails and a couple of cory cats do all the 'work'. - the beauty is nothing gets down under to rot and decay.
(see Aquarium Substrates)

View attachment 122974

I do have lots of rooted plants in this tank, I have six of Amazon Swords, not all the same type but they grow excellent root systems. I do understand about the nitrate factory, I have more nitrates in this tank then in my previous tanks with only a neutral substrate. I was hoping that in time the last bacteria, the anaerobic bacteria that converts nitrate to a harmless gas, would populate my substrate and bio-media and take care of the nitrates. But this has yet to happen, but my tank has only been up for six months and I have heard this can take up to a year.

 

[AbbeysDad]

I was hoping that in time the last bacteria, the anaerobic bacteria that converts nitrate to a harmless gas, would populate my substrate and bio-media and take care of the nitrates.

I can tell you from my own experience that culturing anoxic/anaerobic bacteria to process nitrates into N2 gas can be extremely difficult. I tried for a very long time with Seachem Matrix/De*Nitrate and then I've toyed with Dr. Kevin Novak's Anoxic Biocenosis Clarification Baskets. I've yet to succeed, although there may be a glimmer of hope in the 60g filter. The baskets in the 110g were a bust as the clay litter went mushy.
But it's tough in the highly oxygenated FW aquarium to get the right conditions for the anoxic or anaerobic bacteria to flourish.
Still, if you stay on top of your partial water changes, you should be okay as you build up your bio-filter (which will contain countless micro/macro housekeeping creatures).