its quite silly,
I had some trouble whit a protein layer on the water surface.
It can, and did, help to give the biologic filter a bacteria boost whit some filter material or substrate from another tank. I used akadama substrate from one of my planted tanks, what I should have realised is that it stabilizes the pH at 6.2-6.4 Great for planted community tanks, but not for black water aquariums. :silly: