Low alkalinity high calcium

[Accidentalreefers]

Hey everyone so I'm new to the whole dosing thing, I've noticed my alk has been on a constant decline, it went from 8.2-7.5 after i did a 40% water change my alk still sat at 7.5 so i decided to hand dose Red sea foundation B liquid I run a 75G tank I deducted my displacement and on the calculator it told me to dose 25ML to get back to 8.5dkh i dosed that amount right off the hop I checked my alk a day later and it's at 6.4????? What would be the best thing I do in this case none of my corals are showing signs of stress I'm using Salifert test kit.

Calcium 430
Magnesium 1250

 

[SPR1968]

If your corals are growing they will be using up alkalinity as well as the other elements

I would double check the test result and then add more alkalinity supplement as required. Ideally you dose so it stays at a constant stable level.

Your magnesium is low so I would increase that to around 1300-1350. It’s a vital part of the reef chemistry

Also check the levels in the salt your using or water changes might cause the same problem. 40% is a big change and can affect parameters hence the general guide of 10%