Brains trust! Help me out here with my parameters.

Ammonia: 0

Nitrite: 0

Nitrate: 0

PH: 8.3

Phosphate: 0.125 (approx)

KH/Alk: 7.7

Salinity: 35.5ppt

Temp: 25.2°c

I cannot for the life of me seem to keep / start any nitrate reading.

From everything I've read, I do need some for corals. My solo GH mushroom is thriving, not worried about the coral at all. But I want to add more softs.

I have had some slight swings with salinity creeping up to the 38ppt mark, working on different levels and adjusting my ATO float to fix this. It's slowly staying lower.

I'm doing a weekly 10-15% water change. 8-12Litres. Mixed with the standard Red Sea salt mix. I almost think I'm keeping it too clean, alternatively the algae might be altering the reading.