[Delphinus]

I found that Foz-Down didn't really do a lot for my tank. PO4 would bounce back up within a day. I keep some onhand in case my 65g (which is FOWLR) needs it but I stick to hc-gfo in the reef. It sucks because it's expensive, but it's the only thing that seems to keep it at bay. I change out a cup every week or two. You should be able to get by with less though.

I like having a rabbitfish in the tank because the presence of competition for greens seem to encourage my tangs to eat algae. Without the rabbit in the tank they turn a blind eye to most of it. Personally I like Siganus doliatus because they stay smaller but probably any rabbitfish will do.

Good luck!

Another option instead of a seahare is an abalone. However, they're probably harder to source, not quite as effective as a seahare, and can take a while to acclimate to a tank (last few literally sat in one spot for weeks before waking up). But they're really cool creatures and unlike seahares can adapt to other foods so tend not to starve out once all the HA is gone..