Freshwater Liverock

[Reefmonkey]

We all understand the impracticality of keeping live plants in our African Cichlid tanks, and accept that keeping our nitrogenous waste levels down in solely dependent on filtration, microbiological activity, and water changes.

Or is it?

I have Texas holey rock limestone throughout my setup for caves, structure, etc. This rock is covered in places that get direct light with a rather attractive carpet of green algae. Not only does it look nice and make the aquarium look more natural, the fish like to browse on it from time to time, and I can't help but think that it also is intaking nitrogenous wastes and cleaning the water in a similar fashion to saltwater liverock. The algae seems to prefer the limestone, as I don't get a lot of bad buildup on gravel or glass.

Has anyone read any interesting articles on the idea of "freshwater liverock?"

 

[Stephen]

It's the first time I've even heard of the coined term. Maybe you get to define it?

 

[Reefmonkey]

I'm going to go register the trademark.

 

[Devilishturtles]

I think it sounds good, but the idea of tons of rocks in a freshwater tank is usually just not wanted. I mean, nitrifying bacteria are surface dwellers, and with more rock in the tank there will be more surface to inhabit, you are right. Will it help in the sense that it should be used as filtration? Hard to say. Maybe you should do an experiment. Identical tanks with identical fish, filtrations, etc. one with lots of rock and one with less and see if nitrates climb less.

 

[tkos]

It won't be alive in the same respect, that is covered in microscopic/macroscopic citters and plants. But it is a surface that can hold onto bacteria so by all means it should work fine. But all bacteria that we are concerned with need oxygen, so good water flow will be important. For that reason you will still need filters or else powerheads to create current.

 

[Blazeherd2306]

I thought about this for awhile. The whole point of putting alot of rock in a freshwater tank would be to culture not only aerobic bacteria, but also anaerobic bacteria to convert nitrate into nitrogenous gas.

Nitrates aren't really a big concern for freshwater tanks though. It's so easy to do water changes to keep NO3 levels down.

 

[Jchillin]

I've never seen anything written on the subject but in the case presented, your limestone acting as a biological filter is exactly correct. Depending on the type of algae you are cultivating, it is taking up nutrients (light, NO3, NH3/4) in the same way plants do. The bacterial colonies inhabiting the rock surfaces and on top of the algae growth would be the same in any event simply because they like to adhere to any surface available.

For what it's worth, if you are happy with the look by all means keep it. However, it is not the same as the cured live rock used in SW.

 

[Reefmonkey]

I think it sounds good, but the idea of tons of rocks in a freshwater tank is usually just not wanted. )

As my tank is African cichlids, mbunas, etc., rockwork as cover for the fish is necessary, anyway. The possibility of the algae on the rocks contributing to better water qualitiy is just an added plus. Besides, the algae is a nice food source for the fish.

It won't be alive in the same respect, that is covered in microscopic/macroscopic citters and plants. But it is a surface that can hold onto bacteria so by all means it should work fine. But all bacteria that we are concerned with need oxygen, so good water flow will be important. For that reason you will still need filters or else powerheads to create current.

But it is covered with microscope/macroscopic organisms and plants. The algae is a simple plant, and there is certainly nitrifying bacteria, maybe diatoms, even some protists that may have hitchhiked into my tank, all which has colonized the rock. What is cured SW live rock but a porous, calcium-based rock upon which microorganisms and other organisms have colonized? My limestone is a semiporous calcium-based rock upon which microorganisms and other organisms have colonized. IT's not going to have nearly the same efficiency as live rock of course, but at the heart, the principle is the same.

My primary filtration/circulation is from my canister filter, so any beneficial effect from the algae and other organisms on the rock is just gravy. Plus, it adds a little green to the tank that the fish don't tear up and which looks better than plastic plants.