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
25 Gal. 54watt, DIY CO2 5 Angelfish, 1 male dwarf gourami + 2 females ,2 female betas, 3 albino corys, 2 pepper corys, 2 CAEs
15 gal. Dwarf gourami fry tank
10 Gal 3 variatus platies, 4 black sailfin mollies- 5 Gal guppy birth tank with dividers
5 Gal guppy frytank
1 Gal guppy frytank
40 Gal Pond with 10 female guppies, 1 male tons of fry.
On various pieces of furniture, 6 cats!