Hello,
I use peat granules as a very thin ground layer – just covering the ground in not more than the grain size. I experienced it as very stable, keeping it’s grain form for months – until it’s time to clean the whole tank anyway.
Second, I fill in dried beech and oak leaves, scalded before with boiling water. Not too many leaves – let’s say a layer of single leaves side by side. And one catappa leaf per tank. If available, sometimes I put in some peat moss (you get it as an orchid substrate). If it’s still moist you can take it as it is, if it is already dried, you have to soak it for a while in boiling water. The fish love to dive under this layer of leaves and fibres, and there always developes a good micro fauna which supplies very young fry (which you haven’t even noticed) with the first food.
And third, I use pure rain water “enriched” with humic acids by hanging a nylon stocking filled with black peat into the water for some days – before I fill the water in the tank.
I use the same water for water changes – I change about 25% almost every week.
This way I achieve water parameters of about 40 to 50 µS, no measurable hardness, and pH levels between 4,2 and 5,5.