Sorry for the delay... I don't check in here often any more, but the tank is surviving. At the beginning of 2023 I moved everything to a 10 that I partitioned for a filter/heater/pump chamber.
Lost the hermit crab last summer, recently replaced it with another blue leg who has been absolutely chowing down on the algae like an absolute champ. I have been vaccilating for a long time over whether or not I'm really ready for corals but I decided I had to finally just try something and see if I (and the tank) could handle it, so to that end I added a zoanthid frag.
Still very early on that one and only time will tell if I can keep it happy, but so far it seems to be acclimating well.
The caulerpa and aiptasia have completely disappeared. Now most of the inhabitants of the tank are tiny isopods and digitate hydroids. I also lost the molly after a while and have not repeated that experiment, but I would like to try another fish in here: probably either a watchman or neon goby, or possibly a clownfish. My ultimate goal with this tank was clownfish, but I still don't feel quite prepared enough to care for marine fish. As my kids get older and more independent I hope to have more time and energy for my aquaria again!