Mystix212;1668491; said:Driftwood will soften the hardness and lower the pH. Not by any substantial amount, but your south american fish will like you for adding the wood in.
japes;1668403; said:It's called Tannins, many pieces will do it for months or years.
Best solution without a doubt, Seachem Purigen. This product is nothing short of brilliant, I will never own another tank that doesn't have Purigen running inside it's filter.