Zonthids not happy....

So I have a 12 gallon JBJ nano cube with an extra hydor nano powerhead that blows at the front glass so the current in the tank is not directly on any of the coral. pH is 8ish, 0 ammonia, 0 nitrate, 0 nitrite, weekly 10-20% water changes, 8 hour light cycle with 10 hour moonlight cycle, blah, blah, blah.

So the star polyp, aussie torch coral, clove coral, ricordia, mushrooms, bambam zoa, and three other corals the name of which escapes me right now are all happy, happy, happy...

However, my three large group of zoanthids are closed up tight and won't open. One of the largest rocks is now taken over by hair algae, but the other zoa (except the Bam Bam which is happy) don't have any algae and they are also closed up tight. They were all very happy until about two weeks ago when I added a touch too much 'Fuel' (a coral growth chemical) and got a brown diatom bloom. They closed up and haven't opened since. Some of them have actually died and fallen off.

Help! is there any way to save my zoa?!!

Well to start out there is no magic 'fuel' to make a coral grow... Use the tried and true methods to get good growth: bright light and good water parameters. I would avoid adding any of the chemicals outside of what you can test for (CA, ALK, MAG) as you never know what is the right amount and how much is still in the aquarium...

To correct the issue: Do some large water changes to dilute the chemical. If you don't run carbon, get some and run it to try remove anything it can. If you have a polyfilter available toss it in the sump or other filter and let it pull out anything it can as well. Mainly do water changes until you have diluted that 'fuel' down to as little as possible.

Zoas are hard to kill typically so if this stuff killed zoas, I'd be tossing it right into the trash... Hopefully everything pulls through for you.

Zoa do sometimes just close up for long periods, sometimes they die off, sometimes they open back up eventually. Most do like a lot of flow so maybe try moving them to a more turbulent area and add some carbon, you can take a toothbrush and clean off the ones with algae too.

I notice you have a 12 gal what is your evaporation rate and how often do you top off to keep your salinity stable? or are you using some type of top off if your going threw major Salinity swings your corals won't like that too.