I don't understand why you change 40% of the water every 2 weeks.
Nitrate was 30ppm?
Make sure the test kit is ok and not expired.
I didn't' try that substrate yet, but I've heard that has metals. You must like the look of it. The substrate has metals and IMO shouldn't be part of any salt water tank! If you want to test that please use a magnetic you will have the black sand attaching to it.
Another observation I would like to make is that if you need to do so many water changes and have a biopellets reactor I would assume is because of the nitrates. I believe it's not working, right? Could that be the reason for the zoas to close? Could be part of it, but hard to know exactly.
Please tell us more about the problems you've had in the past and why you change so much water and so often. Why did you add the biopellets reactor and when?
Did you have the zoas closed before you added the biopellet reactor?
I would say you skimmer is ok and it's probably doing some good work, but you really can't rely 100% on any skimmer to do "it's job on removing the excess bacteria with the nitrates".
I would stop the biopellets reactor today and see if the zoas open after next water change.
I would change only 10% at a time. You could keep the 2 weeks schedule.
That could be it!
And if you are willing to change the substrate please remove it by siphoning while do the water changes. You can replace it slowly by aragonite. I like the sugar size oolitic by Caribe Sea.
The zoas could be irritated by the sand?!?!
Lights? Photoperiod?
Sudden changes recently?
Grandis.
I do a 40% water change every two weeks because over the past 10 years that's what has brought me the best results. I'm not saying that everyone should do it but my coral's colors and growth do best when I personally keep things on that schedule. I know it's not the "norm" but like everything else in this hobby, what works for one person doesn't always work for everyone.
The test kit is not expired and it's a Salifert. Again I'll be testing tonight and post the results.
I've been using this substrate for almost 2 years now with no problems. I've kept anemones, clams, shrimp, and many other inverts with no problems. I can keep and grow SPS, LPS, and softies (including zoanthids) as well when using this substrate. To me the black sand makes the corals stand out more. As far as it containing metals I've never heard that. I've done the magnet test on it, and just did it again to be safe, and it does not stick. It is reef safe but does not provide the buffering capabilities that aragonite type sands do.
I recently switched from two smaller frag tanks to the current one (about 2 months ago). The biopellets reactor was taken offline during the move and put back online about one month ago. It can take 4 to 8 weeks before the biopellets take effect so hopefully soon I can slow down on the water changes. Also, when I say 40% I mean 40% of the frag tank, I should have mentioned I'm not including the sump volume in that. So in reality it's more like 25%.
These zoanthids were not put in this tank until maybe two weeks ago. Like I said though all other zoanthids are doing great. As a matter of fact all my corals in this system are doing great including LSP, SPS, and softies. These are the only problem coral at the moment. I'll include some photos of some other corals that are currently in this system and were taken since this one type of zoanthid has closed up.
I dont' plan to remove the sand only because I've been using it for so long in so many different system with no problems. I also put one frag of this type of zoanthid in my display tank last night. That tank doesn't have this substrate so if they open up then maybe I'll revisit that. It's also not using biopellets right now.
The lights are 2 ATI Sunpower 6 bulbs fixtures. They're 18" off the water with no acrylic shields. Two bulbs comes on at 4:30PM and the other 4 at 5:00PM. They shut down to two bulbs at 11:30PM and go completely out at midnight. Bulbs mix is 4 ATI Blue Plus, 1 ATI Aquablue special, and 1 Coral Plus per fixture.
