I'm also having an issue still with my 24 gallon it bottomed out on phosphate and my digi all paled then died, my lps aren't as big as they used to be and I've tried upping my feeding ,but I only have 3 fish so cant put too much in and I still cant get a colour on my salifert kit or a reading on hanna.
I have looked into dosing phosphates now and I'm going down the diy solution using mono potassium phosphate 99.9% off of ebay for 200g, and when it comes im going to make a stock solution. And start on a low dose and see what happens. I have no sump, skimmer or refugium I dont run gfo. All my sps grew like mad and were really bright and vibrant, my lps I was having to frag, then over the course of months I think they starved themselves paled then died, I had cyano now a little dino I do t do water changes very often maybe 6 weeks of 10%. I didnt even think zero phosphates was the problem and wish I knew this months ago.
This is the write up on the product.
I have never dosed phosphates so i dont know how often I'll need to dose but i hope i can turn the tank back around to what it was.I hope you get yours back aswel, as this hobby can be so rewarding in the efforts we as reef keepers put in, then something that you miss takes all your hard work away.
And dont talk about those pesky red planaria, I had to spend 3 days 2 hrs at a time siphoning them out of my sons 35l nano after someone gave me some coral frags for free and I stupidly didnt dip them, then 2 weeks later his 160 gallon crashed after he had a mass red planaria die off (his house stank!)
and lost nearly all corals and fish. I didnt even look for them in my sons tank until he told me there were hundreds. I used flatworm exit twice on it, but only once I'd sucked about 95% out. Good luck.