acropora extension at night and alkalinity question...

[flipteg]

i am pretty new at acroporas but i was wondering, how come the polyps of acroporas are usually fully extended at night when all the other corals in my tank are retracted...? during light hours, the acroporas are extended but during light off, the polyps just extends so much further out...

also, i unknowingly let my alkalinity drop to 7 dKH... my target is right around 9... this is the effect of under dosing a 2 part additive... i noticed it 3 days ago and right then, i started dosing more of C-Balance... now, my alkalinity is back up to 8 and i notice that the polyps on the acropora that i bought about 2 weeks ago has extended out much more than i have ever seen it do... does raising the alkalinity have so much to do with it...?

 

[zoazoa]

Well...
It depends on acropota type. Some extend at night and some do not extend at night.
Alkalinity is very important one for acro so make them entend much polyps.
Anyway polyps extension is a good parameter to show acro is healthy.