Closed zoanthids

[tmgill81]

Over the past 6 months some of my zoanthids have been staying closed for several weeks. When they re-open they are much smaller and dome-shaped. Some return to normal size and some don't. Eventually the same zoanthids repeat the same patter and it appears to be on a cycle, but I have no data or evidence for this. I have not noticed any pest to the naked eye, but at one point I did have a large population of large predatory amphipods. When the large amphipods were present I lost 3 palythoa frags. The odd thing is some of the zoanthids and palythoas have never been affected. Has anyone had similar propblems?

Current Water Quality Parameters:

pH: 8.2
Salinity: 33 ppt
Temp: 78.5-80.0 F
KH: 10
Calcium 400 ppm
Mg: 1180 -1250 ppm
NH4+/NH3: 0 ppm
NO2: 0 ppm
NO3: 0 - trace

System:

Tank: 8 gal cube - 14 gallon total water volume.
Lighting: 150w metal halide about 12" above the water and on for 5 hours a day.
Flow: MP-10
Filtration: 200 micron filter sock, Aqauticlife protein skimmer, and chaetomorpha spp.
Supplements: C-Balance 2.5 mL of A/B 3 times a week, Brightwell Coral Amino -2 drops daily, Tech-M Mg 10 mL 2-3 times a week.
Controller: Everything is controlled by a Reef keeper Lite except dosing.
Water Exchange: 1 gal per week w/ Red Sea Coral Pro Salt

 

[Lazcar45]

I had a similar problem with a colony of eagle eyes. I had a TON of amphipods crawling on them and they never reopened and eventually melted away, I got a flame hawk fish and it went to town on those little buggers, I have read so many posts saying that amphipods wont eat them but could cause irritation to them, but im convinced other wise, I searched that colony so many times for Nudi's, and never saw any. After the flame hawk knocked their numbers down i bought another colony of eagle eyes and they have been fine every sense. Maybe it wasn't the amphipods, maybe it was.......