GFO can be a quick fix, but it doesn’t deal with the problem. Also, you have to be careful that you don’t drop it too fast.So how do you recommend rectifying this?
GFO?
Sources of phosphate are common in pellets and frozen foods. So you can check there.
Did you start with live rock or dry rock? In my experience, dry rock will absorb phosphates and then suddenly put them back into the water. Happened to me. You’ve got 0 phosphate and nitrate then BAM they go sky high.
A refugium with macro algae can help too.

