Zoanthids won't open...help please

[basssnake]

About 2/3 of my zoanthids in my 85 gallon tank haven't been opening for about the last week. Nothing has changed in the system that i am aware of. I haven't added any new corals(and there is only a couple leathers: one devils hand and a about three colt type corals and they have been in the system for a few years). The water flow in this sytem is only from the return pump which is a mag 3(350 gph) but that has been the same for the last 5 years. I checked the water parameters and are as follows: ammonia 0ppm, nitrite 0 ppm and nitrates 0ppm. I didn't check phosphate levels though. The salinity is between 1.023 and 1.025(lower number after top off). I done my supplements a week ago and added last night calcium and strontium/molbednum.

Oh forgot: there is about probably around 1000 polyps in this tank and they are all over the tank. So not limited to one spot with the non opening issue.

Any suggestions to what could be the issue? Any suggestions on what to do? I am not sure what is going on at all. thanks for any help.

[650-IS350]

When you say polyps what type? zoanthid, Protopalys, bottom polyps ????

Polyps usually like good flow or better

What is your pH, Alk/DKH, Temp?

Do you run carbon?

[basssnake]

It is my zoanthids that are at issue. Palys are doing fine. My ph was like at around 8.0 so i added some reef buffer to bring it back up. I haven't got a test kit for Alk/dkh, so not sure. Temp has been around the 75 to 78 degree range. It has been varying a little and dropping some at night due to house temp not being consistent. I would say it is around 78 to 79 and dropping to around 75 or so by morning. Could that be doing it?

[basssnake]

Anyone have some input??

[sps1206]

Do you have any fish or other inhabitants in the tank that could be picking at the polyps? Maybe if your fish aren't eating what you are feeding them and they are starting to get hungry and pick at the corals.

[650-IS350]

when my Alk/pH/DKH are off, not all get irritated right away, some polyps react faster to parameter differences...

that's not that bad of a temp shift, i'm thinking if you don't have any predation, then it'll be your alk/pH