Too high ph. Help

[NaCL+H2O]

So I have a 90G Tank with 100lbs of live rock one tang one clown fish and one hammer coral and sump/refugium. My PH has never been lower then 8.4 and as of recently with the upgrade from a 950gph return pump to a 1800gph return pump my PH is 8.5-8.6. I'm starting to dose KALK very slowly and noticing my PH rise a even more!!!. I already know Im too high so how the HELL do I lower this thing.

 

[Downbeach]

What are you using to test with? Is your skimmer working? Is the tank covered? Vinegar, club soda and Lemon juice is a quick fix. I'd stop using the kalk for now, it will raise your pH. What is your Alk reading?

 

[Dr. Reef Verified Sponsor]

i have a feeling its testing error. specially if ur relying on ph probes backed by controller. they tend to swing out of range a lot.

 

[Ecvernon]

Your bioload sea very light for 90 gallon. How many corals do you have? You may not need to be dosing kalk at all.