I have an established 20 gallon long - been running with current stock for probably 5+ years now. I don't want to replace the whole substrate, but I was thinking of adding an area of controsoil behind a driftwood 'retaining wall' to have a few sword plants.
I know that controsoil is supposed to not leach ammonia like aquasoil does - would I need to worry about that at all (ie put it in a bucket first) or am I good to just dump it straight in?
My second question is that I have read that controsoil has some buffering capacity and will absorb GH. My tank is *very* soft - reading as less than 30ppm GH on the API test strips, and the KH is less than 40ppm. My South American fish are all very happy with this, and I'm worried that adding this soil will pull it even lower, or throw something off balance? I'd prefer a totally inert substrate if one exists, but I don't know if that's impossible when it comes to substrates that can hold nutrients. If that is the case, should I put it in a bucket before hand with an increased GH/KH, so that it reaches it's buffering capacity before being introduced to the aquarium?
Lastly, I saw on another thread here that controsoil shouldn't be used with fish that will sift through it? I wasn't able to find this on the manufacturer's website, but I'd like to check that, as I have kuhli loaches and I wouldn't want to put them at any risk.
My intention is to siphon out the sand currently where I want the soil to go, add the soil, and put the sand back in in other parts of the tank where I'd like to have a little bit deeper.