Yeah 7.8 isn't the end of the world. But, to answer your question. Some ways to raise your ph
Run your protein skimmer air intake outdoors. If you are on an external wall you can do this, or if you get creative and are able to run a lengthy air line running through the house. One way or another. Get that air intake pulling air from outdoors.
Install a co2 scrubbing canister on your skimmers air intake. It's a canister filled with a media called soda lime. It absorbs co2 in the air before that air is injected into the skimmer. The skimmer being a large part of your tanks gas exchange will then be putting less co2 into the water.
Drip kalkwasser. Not recommended unless you're regularly testing alkalinity and are registering a regular drop in your levels due to coral consumption. Kalkwasser use without corals consuming the excess calcium and alkalinity will lead to buildup in the water of potentially toxic levels.
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