I have had several fish die in the past few months, and I lost most of my corals about 6 months ago. I'm just seeing the corals that lived start to grow again! I thought it might be a good idea to do a good cleaning.
Or worse yet, clean and it gets worse.
I don't recall reading about anyone breaking a tank down in order to clean it. I just did a reef central search for tank cleaning and what you describe isn't in the top 15 posts.
I agree. Find out what's really wrong before taking what I think may be a drastic step.
after 7 years.... you should test No3 and Po3, without a doubt they are higher than they should be. The higher nutrients is why you have excess algae (fuzzy) . I have never removed my rocks to clean them (almost at 7yrs now too), but I do - on a rotating basis, clean/siphon the DSB. every 4-5 months I clean 1/4 section. This helps get the gunk and deep settling debree out. I have a sulfur denitrator for No3, and run GFO + drip lanthanum chloride for PO4.