90g tank not doing so good would like to sell it all and start fresh

[The Guy]

First figure out what's causing the problem, the first thing I would be doing is taking at least half of the sand base out, it looks like it's loaded with detris and very dirty, then run some Rowaphos in a reactor for your phosphate issue along with weekly 25% RO water changes, then work on the aptasia problem filefish and some peppermint shrimp. Some more flow to your tank with some water turbulence on your water surface would be a big help, I don't see any water surface breakage in your full tank picture. There could be other issues as well and maybe others will chime in to help out. Hope this helps, with some work and time it can be fixed.