Strange coral behavior

[FishFrik]

I have many different species of corals in my tank, which are acting normally but 2 of them: pagoda cup and red disc. They always start to open up whenever the first light turns on, then after about 30 mins, they will be fully open. About 2 or 3 hours later, they will close up for some reason, even though all lights are still on. They stay closed through out the day.

What does this mean?

TIA

 

[dskidmore]

Could something be irritating them?

 

[melosu58]

Dskidmore might be right but what are your water parameters esp. your PH

 

[FishFrik]

NH3 - .25 (it's been .25 for a week... my test kit might be wrong)
NO2 - .1 (not quite .1 but the result is not clear)
NO3 - 20
PH - 8
SG - 1.026

These parameters are not good due to the fact the 75G was moved recently. But my disc coral acted this way for more than a month in my old 29G which had 0 NH3, 0 NO2, 5 NO3, 8.4 PH, 1.025 SG. I thought it was just my disc coral that does that but i bought a pagoda cup recently and it's doing that as well.

I had/have no livestock that would pick them these 2 corals.

New update: the pagoda cup's polyps havn't been open for 2 days straight. It seems to be turning brown from its greenish color. Might be the bad water that's doing this. All my other corals are doing great though. My green BTA, which is the most sensitive invert in my tank, seems to be very very happy. I put it in the new tank and it didn't move 1 inch.

 

[Hara]

Any reading of ammonia and/or nitrite would be enough to start killing off a coral. I suspect your ammonia reading is correct seeing as nitrite is also present. Corals are sensitive. I am not sure what makes you say the BTA is the most sensitive invert in the tank. Just because it didnt move, does not mean it is happy. Means it is happy enough where it is as far as lighting and current go. You need to do water changes daily, maybe even twice a day, until the water parameters are PERFECT. You will lose corals if you do not.

 

[FishFrik]

I've beeing doing 5G WC's everyday for a week. Thanks for the suggestion

As I said, my disc coral acted like this for almost 2 months in my 29G (0 NH3, NO2, 5 NO3)

Every corals in my tank (look at myinfo) are doing fine. All my shrimps, snails, crabs, fish are acting normal. I even had 2 sandsifting starfish in my tank (came with the used tank but i sold them). I added a tiny frag of zoos yesterday and it opened up nicely. Weird

Thanks for the replies