Thoughts on SPS polyp extension..

[Aquattro]

What causes polyp extension in SPS, or rather, what causes polyp retraction? I noticed a few months ago that about half my colonies no longer have noticeable extension, day or night. Others are fine, although not what they once were.
I think it started with a change in salt, but returning to my original salt hasn't restored the PE...

Thoughts??

[BlueTang<3]

potassium?

[Aquattro]

Originally Posted by BlueTang<3

potassium?

how so? Not something I've ever tested

And if so, why great PE for a while, but not now? I do 40% water changes bi-weekly.

[Aquattro]

And something else to think about...should there be any daytime PE in the first place? Corals in the wild tend to not extend other than at night (from what I've read). so is something missing in our tanks that they're trying to get? does that mean my tank is supplying it? I have a lot of light, perhaps they get enough from photosynthesis?
So is daytime PE good or bad?

[lastlight]

Good question. Has it ever been shown to be a good sign to have massive PE? I know I like how it looks but I'm curious to hear if anyone knows more about this.

I will say that I never see corals on their way our with great PE.

[Aquattro]

Originally Posted by lastlight

I will say that I never see corals on their way our with great PE.

Agreed, although none of mine are on their way out either. Growing well, good color, etc, just not the PE they used to have. I even have a milli that is barely extending!

[PoonTang]

I had the same problem. Fought it for months and months and tried everything from additives to new salts to massive water changes. It turned out to be a tiny little yellow coral goby whom I had never ever seen nip at a coral. But within a week of him being moved to the nano tank my polyps came back.

[Haloreef]

I had massive extention in most of my Sps colonies for a long time and then they just stopped! I tried every thing and finaly narrowed it down to a small voltage leak. I spent 14 bucks on a Rid Volt and within hours the extention was back!
It could be different problem for you but only $14 dollars out of pocket to try.
Keith.

[Aquattro]

Keith, not a bad idea. I just browsed the tank and noticed that some pieces do have good PE, especially a newly mounted pink lemonade. Pocci colonies all have great extension, as do the birdnests. But some colonies have nothing at all. For 14 bucks, I'll try grounding the tank.

[Delphinus]

Interested to hear the result of that.. Tagging along.

Haven't seen a whole lot of reefs in the wild but the ones I have seen, have all been in the daytime, and I don't ever remember thinking "Boy the polyp extension on these acros is not very good. I wonder if it's better at night time." Everything I've ever seen has all had PE to some degree, acros, porites, etc and eieio, but that said I've never seen the shagginess of a typical prostata or milli. So whether that's because maybe I never saw a prostata or milli where I've been, or if that's just not a natural occurrence, I can't say..