@Pvtgloss
I remember using Fluconazole with mixed success alongside you this spring..... I wanted to update you on my situation as I have learned a lot since that other thread.
In June, my wife and I decided to move homes. I had to breakdown the entire tank in July and move it 400 miles (not fun, do not recommend lol)
During that move, I put most of my rock into large, cheap coolers with bubblers and heaters..... and 'cooked' them for ~8 weeks. ~30% of my rock stayed with the fish and did not get 'cooked'.
I tested the 'cooked' cooler water after a week, and lo and behold my Nitrates were ~5ppm and
Phosphate .12ppm!
I did a ~90% water change, and after another week or two I tested Nitrates at ~1ppm and Phosphate had already gotten back up to .11!
The amount of phosphates that had been bound in my rock was far beyond my expectations. I excessively dosed LaCl daily for the next ~6 weeks and the leeching dropped significantly, but was still leeching.
Earlier this month I finally got the tank rebuilt and put in the rock.
Within two weeks, the ~30% of 'Uncooked' Rock was already covered in GHA and the 'cooked' rock has stayed relatively clean, despite being closer to the lights. My tank parameters were 0 Nitrate and 0 Phosphate. It was clearly a rock problem.
All of this is to say, I'm now a believer that persistent GHA = phosphate-leeching rock, and the only solution is to unbind all of the phosphate over time, or get new rock.
I've now been dosing LaCl to keep phosphates below .02 for almost 3 months and it's still leeching out, but I am seeing progress.
I believe the only three options are:
1) Get new rock
2) Breakdown the tank and 'cook' the rock for an extended period, likely months
3) Dose LaCl or GFO excessively to help strip the rock of phosphate over time. I hypothesize that if you have a GHA jungle, you would have to dose beyond a 0ppm test reading to truly outcompete what the GHA is absorbing.
Good luck!