Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
I have used peat moss in several ways in aquariums.
1) Pure peat moss substrate for carnivorous plants
~It is so light weight that any water movement sends it flying through the tank. It settles, but settles on top of leaves and everything else. As a confined riparium it works really well, but just loose, well, I will not do that again.
2) Mixed with the charcoal colored Soil Master Select
~Similar to above comment: The peat moss tends to fly all over when the substrate is disturbed. The materials are similar in weight, so they stay blended. (I do not think sand or gravel will stay on top as a cap)
3) In the filter: I use a nylon stocking, cut to fit. For example, in small filters a Knee-Hi can be cut into 3 bags. Rubber band one end, zip tie the other. When the rubber band disintegrates it is time to replace the peat. I use about half a knee hi in larger filters. The bag is not too full, the larger bag is easier to stretch into position so it fills the basket of something like the Rena Filstar series. If a filter will hold 2 bags that is OK, too. I used to keep track of how often to swap them out.
In all these uses:
Peat moss varies, so what it may do...
Some peat will exchange a lot of the minerals in the water, sort of like a sodium exchange water softener, so the Ca and Mg levels in the tank may go down. In my case this is not happening very much or at all.
Peat moss releases tannic and other organic acids to the water. This will lower the pH. This is especially true when it is used in a tank with a softening substrate. (Soil Master Select removes the KH from the water, so the pH will certainly drop).
The tannins will stain the water. The amount and color will vary. In my case the water is tinted just a little bit toward gold. Not harsh yellow, not orange or red. Just a little, and it does not last long. I have very clear water in my carnivorous plant riparium. I just moved it, but reused the same substrate.
I also use peat moss to prepare the water for some tanks. I put a knee hi stocking full in a garbage can (20 gallons to 44 gallons, I have 3 water prep cans). If the peat is new the water is prepped in a few hours or overnight. I keep reusing the same peat, and get about half a dozen uses out of it. But it takes longer to prep the water.
I have set up a pump to circulate the water, and the outlet (a vinyl tube) is aimed to pass through the stocking full of peat.
No, do not rinse the peat moss before use, but do wet it.
I put it in the bag (cut off stocking) and squeeze it several times in some water.
Peat moss does not seem to want to get wet. Hot water helps. Do not use surfactants for wetting aquarium peat moss.
I use Canadian Sphagnum Peat Moss purchased in the garden department. Read the label to be sure there are no fertilizers or surfactants. This is a fine, fluffy material, and little bits may escape and drift about in the tank. Not for long, they do settle out.
Peat moss is also available in pellets, packaged by some of the aquarium filter manufacturers (I know Fluval/Hagen has some). These pellets stay cleaner than the garden style of peat moss. They are pretty expensive, though, compared to a bale of the garden variety peat moss.