welcome back to the hobby glb! I'm sorry but I just saw this thread or I would have been posting some encouragement and maybe helped if I could. It sounds like you figured out what happened to the clowns - I'm sorry for the loss but at least it sounds like it wasn't something amiss with the new setup. One piece of advice I have - did you replace the sand? since it was sitting for a while and had the crash, that may help. One other concern would be your rock could be leeching phosphates - but you're doing what you can about that with the phosguard - the only other thing that could really take care of it would be to bleach the rock and then cure it until you get no phosphates. Given that it's a fairly small tank, have you thought about maybe starting over with some new live rock or maybe some dry with supplementing with a couple of pieces of live rock? I'm just thinking stripping down to basically starting again may be your best bet in the long run.
Don't throw in the towel!! You will succeed and you'll be happily watching your beautiful slice of the ocean soon. HTH with at least some ideas.
I think I saw on another thread that you're a female? I'm just always glad to see other girl reefers in the hobby