Polyp Extension Question

[ncny21802]

I recently added SPS into my new tank about 3-4 weeks ago. I have had 2 large setups in the past and started up a new 46 gallon bow. Everything is doing great. My Acros have great polyp extension as do all my monti's. I also have LPS and Zoas in teh tank and they thrive. I run a nutrient rich system and I feed the fish a little too much. I am not a newbie by any means but have a question. I recently upgraded my lighting to a 6X39W ATI Sunpower from the Nova Extreme Pro. I have it about 4 inches above the tank. First few days all was fine but when I got home from work today I noticed the polyps on all my monti's..encrusting and digitata were not extended at all. My Ora Red Planet and Ora Joe the Coral looked great but my Marshall Island Purple/green were retracted. I moved the lights 2 inches higher and within an hour polyps started showing again. Another hour after the main lights went off all the polpys were out on all corals. I run the dusk/dawn for 10 hours and the mainlights for 6. Reducing the photoperiod shouldn't be necessary but would 6 inches above the water be fine? I guess I'll find out when I get home tomorrow, but just curious what others have to say. I'm about 99.9% positive it's the lights but just in case my parameters are:

Nitrate 30
Alk - 9
Cal - 450
Mag - 1400
Salinity - 1.0258
Temp- 80.2
PH- 8.14

Taken at 11pm

I run a SWC 160 skimmer and have a reactor for GFO and ROX Carbon. Mag is a little high so I'm going to stop dosing Mag. I do water changes of 10% every 5 days and have a heavy bioload.

 

[rigleautomotive]

I think you are correct about the light change being the issue.The corals that are more light loving seem to be happy but the lower light corals are showing signs of stress.I would acclimate the corals slowly to the new light,erring on the side of less is better for now and slowly over the course of a few weeks lower to about 4 inches above the tank if possible.GL

 

[westohooligan]

Not to hijack, but I didn't want to start a new thread:

I too have weird issues with polyp extension; they only do it at night. I know this because I can shine a flashlight in the tank and see all my acros with full extension, but not during the day. My millis will extend during the day and retract at night. Can I do anything to get the acros to extend during the day?

 

[ncny21802]

Some coral onyl extend at night, especially wild acros..it's a defense mechanism. Any angels in the tank?

Dan- Thanks for the input. I raised the light to 6 inches above the tank yesterday, when I came home..same issue. Acros happy, monti's not so much. My Jeremy's Monti is usually so extended at day that you can't see the base, only polyps..not so much anymore. So last night I raised it so it is 9 inches above the tank and I reduced the photoperiod to 10 hours dusk/dawn and 5 hours daylight. Only other thing I can think of is to move the corals lower, but I don't want to break them off. Hopefully this last raise will fix it. I can't raise it higher then it is all I could do going forward is reduce the amount of time the lights are on even more but I don't want to upset the acros. Catch 22. The first day with the new lights they were fine, but I think the light got stronger as the 3rd day hit. This light is better long term, but I'd hate to lose corals now. Will it take a week or so for them to adjust and get back to normal at the new levels or will happen instantaneously once they are comfortable again?

 

[rigleautomotive]

Well usually slow steady progression in a positive manner.After a month if what you are doing is the right thing you would notice a big difference compared to when you made the change.

 

[solitude127]

The SunPower is much more powerful than the NEP. So you have another vote of light acclimation. A PAR meter in this case would have been very handy to see the difference in PAR between the two fixtures.

 

[ncny21802]

Thanks to you both. The difference in PAR has to be great as the NEP sits on the tank and is only about 2-3 inches above the water. The Sunpower is now 9 inches above the water. We'll see what it looks like when I get home

 

[Monkeyfish]

I think it's a common misconception to equate polyp extension with coral "happiness." While diving I've seen a lot of corals in the ocean that did NOT have polyps extended. I've yet to see any empirical studies that definitely prove why corals extend their polyps. I've heard several theories including increased respiration, feeding, current and others. The corals may not be extending their polyps under increased lighting because they don't need the added surface area for photosynthesis or they don't need to collect as much nutrients/food from the water column because they are getting more light. Who knows?

 

[ncny21802]

Excellent point...It's not like they are losing color. Here's some pics with the new lights:

Before

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After

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Before

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After
Lights are out and I can't get a picture but the coral is still purple, just not as many green polyps are out. You can kind of see it in the picture above in the background