Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
What fish are you planning to breed? What water conditions are you looking for?
If you want to drop the pH this probably means reducing the KH. Is the GH also up there?
Soil Master Select and Turface reduce the KH and therefore the pH quite well, but do not touch the GH. You might need to do something else to set the GH at the right level to suit the fish, as that is the most important parameter.
If you want to maintain the mineral levels (KH, GH, TDS, pH), then coral sand, or limestone based sand would work.
For a grow out tank I would keep the plants in pots or grow plants that do not need substrate. I keep Guppy Grass in my Endlers tank, for example. When it is time to harvest Endlers I pull out all the Guppy Grass, then toss it back in when I have the fish I need. (Careful: Some fry will hide in the Guppy Grass. I put it in a bucket of water, not just a dry bucket.)