that's interesting. I wouldn't have guessed though that ph of 7.0 was enough to significantly dissolve enough aragonite to be meaningful. It would be interesting to test ca and alk, pre- and post- canister to see the difference. Too bad i chucked out the last bit of reactor media i had, i would have loved to try it - although i don't have a spare filter canister i could have used anyhow. Soooo ... Anyone else want to give it a try and post the ca and alk numbers?