Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Put peat moss in a nylon stocking. Put this in the filter.
ALSO prep the water before the water change. Peat moss removes some of the minerals in the water (see the post above about how the GH and KH drop). You do not want to create swings in GH and KH when you do water changes. Here is how I do it:
Run as much water as I want into a garbage can. Add dechlor. Add a fountain pump on the bottom, aimed straight up through the middle. Put peat moss in a stocking (Knee-Hi full for 20 to 40 gallons of water) set up around the pump intake. (Careful- some pumps can inhale the stocking). Run it overnight. Test. I can re-use this peat moss, but it takes longer to prep the water.
The water is now a lot closer to the tank parameters, and safe for a water change (even if it is not perfect), and removing the minerals and lowering the pH before it goes in the tank makes the peat moss in the filter last longer, since all it is doing is maintaining conditions, or handling a little top off water.
Substrate that removes KH (and therefore allows the pH to drop) include Soil Master Select, and some of the ADA products.
However, if that is ALL you are using you are running this risk:
Over the week or whatever between water changes the water is gradually softening, pH dropping. Fish can handle that. But then you do a water change, and in just a few minutes the water changes drastically, a lot harder and high pH. Fish cannot adjust to such a fast change.
You need to prepare the water ahead of time. Peat moss is probably the cheapest way, but what if you put some of that same substrate in a nylon stocking and ran the water through that? If it softens the water in the tank, and the water is not really flowing through it so much, then it sure should soften the water when the water is pumped through it.