Raul may I suggest you try Tetra blackwater additive, I used it on my tank, and the angels I bought a few weeks back suddenly decided to start opening their fins again and looks happy for a change, also my plants seems to have taken off with about 4 leaves each, one started makeing red leaves, I dunno what its called I can post a pick if you want. And it hardly made my water any darker, the darkness goes away after about 48 hours.
Cape Town, South Africa.
Hi. I'm back.