How much will coral (crushed/chunks) raise ph

Are you just adding this to the sump or adding it as or into the substrate? I would image you would need quite a bit for a 220. I mix it in with some rocks and sand in my 150g, but can't remember how much it was. It does keep a very consistent 7.8 ph when my tap is 6.8-7.0. This has been working for years without adding anything else. I love it. I think I only used a 20lb. bag.

Add it little by little and monitor closely. Also do yourself a favour and get a GH and KH test kit, and learn about hardness and other water parameters like conductivity if you're going to try modify your tap water to emulate the fishes native waters.

My 120g Malawi tank had 80lbs crushed coral. My tap is 7, tank stayed at a steady 8. Careful with water changes though, a few smaller volume, instead of 1 big.