25 g tank 2 years old. Clownfish and electric blue fish, 2 total. Fighting conc, 4 snails (variety), and one emerald and zoas, polyps, Xenia, and a leather coral as my corals. Small protein skimmer I run on occasion. 8-9 hours originally. 7 hours of light now. My zoas went down slowly from day one and never spread. My green polyps have thrived and spread over the last two years. My Xenia has slowly shriveled and died (much like something else) very slowly over the last two years where as the zoas shriveled and died within 6 months. Leather corals are only 3 months but have shriveled. Salinity normal. Temp 76-78. After these issues (most coral but one dying), I have decided that mechanical, biological, and carbon work gfo (chemipure elite) was taking out too much for my corals to thrive. My nitrates ites and phosphates near zero. So now I’m at mechanical and biological only. And of course I have an algae bloom. So, should I let things takes its course ? Or should I add gfo and carbon for a day or so to reduce the drastic change in the water chemistry? Or any other suggestions ? Thanks