Soft corals seem to be shrinking

[wbdevers]

Hey all. I've had my tank up for 9 months and all has been going very well. All of my corals have been doing great and growing. Here lately though, I've noticed that some of my soft corals seem to be shrinking in size and one even died. My SPS and LPS are doing very well as are basically half of my softies. My last water params are: NO3-0, P04-0, pH 8.1, Ca+-420, Mg+-1230, Alk-6.5, temp-84 (usually 82), SG-1.026. I do 10g water changes every other week. I run a BRS media reactor with GFO and GAC.

The corals that are shrinking are my green palys, neon blue/green stripped mushrooms, and my white finger leather died over two days. One colony of zoas has shrunk in size, but they are spreading. Also, they changed from kind of a dark green to a pale green. My large leather coral used to be brownish with green polyps--it's now almost white, but growing as well. My SPS have doubled since I've gotten them. My LPS are doing very well too. Below are some pics to show the size changes.

The only thing I can think of that may be the cause is I changed bulbs. I went from a Hagen and other brand mix to all ATI bulbs. The cause maybe?

Thanks for any help.

Palys in March:
http://i1226.photobucket.com/albums/ee415/bluwtr/Critters/GreenPalyflash3-14-11.jpg

Today:
http://i1226.photobucket.com/albums/ee415/bluwtr/Critters/DSC04296.jpg

Mushrooms in April:
http://i1226.photobucket.com/albums/ee415/bluwtr/Critters/AqNew4-23-11025.jpg

Today:
http://i1226.photobucket.com/albums/ee415/bluwtr/Critters/DSC04297-1.jpg

Zoas in Feb:
http://i1226.photobucket.com/albums/ee415/bluwtr/Critters/GreenZoas2-25.jpg

Today:
http://i1226.photobucket.com/albums/ee415/bluwtr/Critters/AqNew4-23-11018.jpg

and finally, my leather in March:
http://i1226.photobucket.com/albums/ee415/bluwtr/Critters/GL3-5-11.jpg

Today:
http://i1226.photobucket.com/albums/ee415/bluwtr/Critters/DSC04292.jpg

As a side note last Monday my RBTA split for the first time and the daughter is doing great as well.

Sorry for the long post.

[beckbrass]

Some times they just recede but the high temps and low alk are mostlikly not helping.

[wbdevers]

My alk is usually around 8-8.5 and I'm working on lowering my temp. I set the tank up in Sept. so it skipped last summer, but I'm getting the high temps this year. Over fall, winter and spring my temp stayed around 80.

[beckbrass]

You can aim a clip on fan at the surface. It is also ok for your temp to be below 80 if you like. I keep it around 78, this gives me a little more room before it gets to hot in there.

[wbdevers]

Yeah, actually my next purchase will be a fan for the tank. My canopy is rather short so a clip on won't fit. I like keeping my temp arount 80. Closer to natural habitat and speeds metabolism to increase growth, but not too high (like I am now).

[Dashin89]

It could be the lights. I switched to a 4 bulb fixture with ATI bulbs and a lot of the softies did not like it at first. I had to move them down. They eventually adapted.

[Lynnmw1208]

I think some of it might be due to the new bulbs as well. When I switched to ATI bulbs my zoanthids got lighter in color. I don't have any softies though, so I can't help ya there.

[wbdevers]

Thanks all. I'm thinking it is the light level. I wish I could get a PAR reading and see what's at the bottom and top.

Dashin89, couldn't help but notice that we have almost the exact same set up. I've got an RO skimmer as well, but mines a HOB hanging on the sump. Wish I had gone to a 110-125 tank. One day.

[DanEnglish]

I would bet lights, especially looking at the leather. For all the effort we go through to make sure we have enough light, we need to consider sometimes that many corals are not adapted to these levels and actually live in relatively deeper water.

[Potsy]

Back when I had a 75 gallon with 2x250 watt halides, I kept a sacrophyton (toadstool) that wouldn't open up, even on the bottom, until I placed it in the shade of an overhang. Once they're acclimated though, they can take a lot of light. I also had a huge sinularia the size of a basketball that seemed to bask under my 10k halides. When I moved it to a T5 lit tank, it never looked the same.