well theres a couple things you could do. IF thw water is hard alot of those producs wont keep the pH low because they dont effect the hardness and it jsu goes back. There are water softning pillows, that you can put in your filter that as far as i kno obsorb the KH and then you just put them in a saltwater bath to recharge it, alot of people use peat moss too. if i were you i would jsut do little waterchanges to not make a big impact,or have a reseviour of soem sort to pre treat the water to get it were you want it befor adding. other them that maby a RO unit and mix it with water. hopefuly soemone els has more ideas, thats all i can think of.