Help with zoa's

[fishoutawater]

I bought a small green zoa colony about six months ago. It had only about 9 heads. Up until about a month ago it had been doing very well, and had around 35 heads. Now it has dropped slowly down to around 20 and shows no sign of stopping. Lighting, filtration, livestock, etc. etc. has remained unchanged in that time. There are 3 fish in the tank, all doing well, as well as a bubble and torch coral which are thriving as is a small sps, pocilliopora I think. Any ideas?

[Kdocimo90]

have you been keeping up with water changes, and what are your water parameters?

[fishoutawater]

temp. 79
nitrates <5 ppm
calcium 450ish
kh 60mg/l this seems very low?
I have only been changing about 5 gal. per month and up till now have had no trouble. The tank has been established for longer than the 8 months I have had it, I bought it used. Not sure how much longer though. The lighting is 150w halide 14k

[paca444]

I have had seriatopora and acropora do well and then all of a sudden bleach when they are too close to another coral for 3+months.

[rps042657]

Try changing the location in the tank. It has worked on the ones we have. More or less light and flow. Will only take a fews day to tell. We have a Leather that has been all over our tank before we found a spot it liked. Now its huge.

[fishoutawater]

Oops. s.g. is 1.025. Read through a few chemistry links, the alkalinity was very low. I have bumped it up to levels recommended in an article from Randall Holmes Farley using baking soda. My nuisance algae is almost nonexistant so I'm not too concerned with phosphates. Thank you all for your input.

[fishoutawater]

Zoas still declining. Increased flow a little bit, fixed alkalinity problem(does that even matter for zoa's?). No change. I just noticed tonight a couple hours after lights that there are mysis shrimp crawling all over the zoas. What do mysis eat? Ive never heard of it, but is there any chance they are munching on them? Ive been watching for over an hour now and every time I check there are always 2 or 3 of them there.

[returnofsid]

do some picture searches for Zoanthid eating nudibranchs. I've personally never seen one...and HOPE I never do. I also hope that's not your problem but I've read a lot about them recently. What fish do you have in there? Sometimes some tangs will take a liking to them, as well as most dwarf angels, though my Coral Beauty has never bothered mine. I have seen my pistol shrimp snip them now and then though. I've also heard of Emerald crabs doing this.

When you say declining, are they just staying closed up? Sometimes mine will do that for a period of a week or so and then come out of it just fine. Is there any detritus build up on them?

[fishoutawater]

I have an algae blenny, saddleback clown and a small mandarin. All fish have been for tank for a minimum of 3 months. The last addition was the mandarin. Please no yelling, I will be upgrading soon and for now my fuge and tank are sustaining him. He is small, 2-2 1/2". Declining meaning I had 35 heads 2 months ago and now have only a dozen. The heads are opening daily, but they seem to atrophy by the day until they get to a certain point and then stop opening. After that the stalk just withers away til its gone. Also no detritus or algae on or around. Flow is about 30x tank volume, and they are not in direct current.