question.

scenerio: assume both tanks have the same setup equipment.

tank1:
an acro is healthy and very nicely colored with med polyp extention

tank2:
same acro, color is faded but polyp extention is super extended.

what would be some possible reasons for the super exended polps in tank2 with loss of coloration vs. the nicely colored acro in tank 1 with med polyp extention?

what factors contribute to the extention of polyps on sps corals.

Are the bulbs the same? Both the same strength, type (and that does make a difference), both the same age and with the same number of on hours of use?

assume both have the same equipment setup and run the same

lol how can u assume those factors tho? because i think those factors do play a big role in determining the cause.

ok, then how does lighting play a role in polyp extention?

well the intensity of the light. whether its 10K , 14K, 20K. whether its metal halide or pc. whether its old bulb or new bulb. all of which may not be the same

so your saying your lighting entensity is what determines the amount of polyp extention?

I would not have necessaily jumped to the conclusion that the polyp extention was due to light differences. But you also mentioned that the one coral was faded as far as coloring. Two of those together can point to the lighting. IMO.

ok, i would like to ask...
are you experiencing a problem or is this really a hypothetical question..

if it's real, lets get into the details, if not, hypothetical situations like this are rare and hard to give details on.

i have never seen two full systems setup "the same" there are always some differences

hypothetical question,
ok let forget the two systems being alike and focus just on polyp extention.

ex.
2 frags from the same colony
1 would be brighter and more colorful, but have less polyp extention in one system and another in a different system would be more dull and less colorfull, but have greater polyp extention.

breaking down the question:
y would a nice healthy looking sps have less PE than a less healthy looking sps.
healthy meaning (banging coloration, how it should look.... i guess)

is it because of O2 levels, feedings, lighting?

my theory was low o2 levels might cause more polyp extentions. example being at night, polyp extention is greater maybe because 02 level is lower than the day due to the lack of photosynthysis.

or maybe its due to lighting like iglowce said. i just wanted a backup to that answer or anyother theories.

interested in what you folks think.

latez

K, maybe I should address it this way. And if it doesn't help you out it's the best I got.

If I have a coral for poor polyp extension I would look to...

inappropriate or insufficient waterflow
excessive illumination
predatation
allelopathy
agitation


But there are many many other reason. Of course, O2 has something to do with it... nothing thrives in low O2 environment... a non thriving coral would have poor polyp extension. O2 ties in with REDOX which ties in with coral heath.

It could be circulation too. Even with the same equipment the placement/shape of LR & corals could affect the flow. Jake Adams has a really good series in Advanced Aquarist's Online Magazine - Advanced Aquarist's Online Magazine (http://www.advancedaquarist.com/) You can search on water flow is more important and find all of the articles. Here is a link to Part 1 Advanced Aquarist's Online Magazine - Feature Article: Water flow is more important for corals than light. Part 1. Introduction to Gas Exchange Y
(http://www.advancedaquarist.com/2006/6/aafeature2)

RealChange,
unfortunatly you hit apon a topic that really doenst not have an answer.
you can ask it of 20 peopel and i assure you that you will find at lesat that many answers.
there are so many things that "might" contribute, but the fact is to my knowledge no one is really "sure"

i have heard all of the items listen above and more
many are contradictory,
like low nutrients or high nutrients
too much light, or not enough light.
too much or not enough calcium
even time of day/night could affect this

this is why you see such a variation in coral.
you can take one beautiful Acropora, frag it, put two frags in the same system
now you have the mother colony and 2 frags.. you could end up with all three looking the same, or three different looking corals.

i have moved corals from one place to another and seen they change

i guess what im really getting at is dont worry about polyps extension, as long as the coral is healthy and growing (degree of extenion is not always an accurate indicator of health)
once you are sure you have that, just make small tweaks to the system or positioning and see how the specimen reacts, each coral is different. what works for one, wont work for another..

i hope this doesn't discourage you, i don't mean to say the answer is not out there, im just saying in my years i have never seen anyone give it from a facts (with scientific testing vs anecdotal standpoint