Hi fellows,

from my recent observations across more than one of my tank (totally different environment, i.e. bare & planted; using tap water from different sources), I observed that my tank water consistently dipped to pH 5.0 (& possibly eve lower, as the test kit scale has nothing beyond 5.0).

I should be commissioning another tank in a month's time, & I'd really like something to keep the pH stable at say, 6.x, for sustained periods. Coincidentally, I was also looking for some extra filter bio-media, & I noticed that Power House's filter media claims to be able to maintain the pH at a certain level (which Power House also never specify). The following is extracted from the product description:

Hard Type's pH Rise Controlling Principal
The main component of Power House Hard Type products is calcium silicate crystalline wollastonite. When water begins to oxidize, the product releases calcium ions, controlling the drop of pH level. Different from calcium carbonate (such as coral sand) which constantly emits calcium, the product releases calcium ions when necessary and controls drop in pH level, making it safe not only for saltwater fish and African cichlids, but also for aquariums for discus and arowana which tend to drop in pH level.
While that sounds promising, I have not used that media after all. Any testaments to its claims (specifically, the pH-locking)? Or are there more textbook methods of preventing tank water's pH from dropping below 6.0?

N.B. I do not want to rise it above pH 7.0 either.