peat moss is a good idea and i used to use them for carnivorous plants because if its acidicity. But peat moss will stain my water yellow/brown because of the tannins that it gives off. if i remember right i saw "pH decrease" chemicals at petsmart. are those any good?

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55gallon
Light - 6500K CFL, 23wattsx5 5hr/day
Substrate - Red Mexican Clay, Sphagnum Peat moss, Eco-Complete
Misc- Pressurized CO2, EI Dose KNO3, KH2PO4, CSM-B
Plants -Limnophila Aromatica, Stargrass, Dwarf Hair Grass, Christmas Moss, Baby Tears (HM), Dwarf Baby Tears(HC), Rotala Rotundifolia, Ludwigia Glandulosa, Riccia Fluitans