I would do a 30-50% water change and add carbon. The dying corals are going to be part of the problem. Send out an ICP test. What do you use to test now? Your alk seems a little low. A water change should help. If not enough, I'd dose but the WC should be enough. Take a par reading. And stop...
So I haven't bought a fish in a few years and just recently had a tank crash. I remember Salgado aquatics had good prices but I see they closed.
Is there any shop that doesn't charge $40 for just a plain clownfish?