ph up

I am trying to raise the ph of my Malawi tank with little success. I have used about 4kg of limestone rock in the tank as well as about 200g of crushed coral in the filter and the ph is still at 7. I have ordered another 1kg of crushed coral for my filter. Do you think this will be enough to...

Hey all, We're beginning to run into a new problem. Over the past several weeks our ph has been slowly dropping, to where now it's about 6.8. A few weeks ago it was holding steady at about 7.6-7.8. I know that our fish prefer the lower ph so it isn't an issue at the moment, but we don't know...