CaribSea Aragonite Rubble Zone for raising PH??

[NW Cichlid Keith]

Has anyone use this to raise PH? I have a 300 filtered by sponges and an Eheim 2262 w/ Pond Matrix. It has pool filter sand substrate, only a couple pieces of driftwood, and is moderately stocked w/ mostly Amphilophus. Tap water comes out around 6.9 and is VERY soft. I do 80% water changes weekly, always have zero amonia and nitrite - nitrate is usually around 10 when I do the water change. All is well, except the PH will drop to around 6.0 - not good for these guys. I can pull the two pieces of mopani wood (not sure how much this will help), potentially remove all the pool filter sand and replace w/ aragonite sand (would prefer not to), but know I need to do something. Anyone have good luck w/ the rubble zone and if so, how much would your recommend for a 300? Thanks,

 

[TwoHedWlf]

Looks like it's basically just coarsely crushed coral?

I use a couple handfuls of coral fingers in my filters. Works well in my 4 foot.

 

[duanes]

I have used the fine grade aragonite as media in fluidized bed reactors to help maintain alkalinity. It worked well bringing buffering capacity to equilibrium.
I had to add more periodically as it dissolved, and when adding new, it sometimes gave the water a temporary milky appearance. You can see that in the little fry tank in the 2nd photo.

 

[RD.]

One of the best (and cheapest) ways to raise alkalinity is by adding media bags filled with pre-washed crushed oyster shell to ones filters. Crushed oyster shell can be purchased in bulk at any local farm feed center. (sold as chicken grit) Initially rinse the crap out of it, then simply replenish when required. No need to change anything in the tank itself.