Coral are receding whats wrong

[Mike E 6453]

My corals have stopped coming out. I have a plate coral and the rock under it is starting to show, and his tenicales don't come out anymore. I also have another coral that doesn't extend it's tenicals any more. It just looks like a bright green rock. I have recently started using premixed salt water, but it isn't affecting anything else. I stopped doing the pre-mixed a while ago, but i can't figure out what is going on. What do I need to test or change to make sure that the coral are doing okay? please help.
Mike

[Alice]

Give us a run down on tank parameters; temp, salinity, pH, alk, nitrates, type and intensity of lights, water circulatuion. That gives us a place to start.

Are you feeding the corals? Plate corals are big eaters and often, without feeding they will waste away.

[tims]

run some fresh carbon if yo have it too. if there is something in the water that should pull it out..but lighting? ph? amm? ....

[Mike E 6453]

The pH is 8.3, Nitrates are about 20 right now, usually close to 0 though, the temp is 78, salinity is at 1.024, and i have a coralife 130W. I think that is everything, and it is all pretty close to correct right? Let me know if I need to be testing for more things to get to the root of the problem, and yes i feed the coral black powder and I feed the plate coral frozed brine with a baster once a week. He is actually looking better but the other one that has the long tenicales in getting worse. Everything else looks great, it's kinda weird. Thanks for the relpys.
Mike

[tims]

mike, i do not have a plate coral cause' my lighting is not good enough for one yet , but my research on them is..

they need a med to strong lighting..perphaps MH.. but i think you diff. need to get the nitrates down a bit.. also plates do not like a heavy flow, and reg . a good amount of calicum. did you test for that? if not get a test kit for it. plates need in the upper 430- 480 ppm or so..if you do not have a good cal. level that could be it. but... they are a harder coral to care for from what i have read so far..some have great luck others do not.LPS can be very picky..

HTH

[yardboy]

What kind of skimmer you got? After two years with as many as 6 tanks at a time, I've decided that the biggest problems (mistakes) I've had are too high a level of organics in the water. Water changes and high performance skimming have mostly cured me of everything.
I've got two plates and they've been amazingly resilient to my blundering. I have noticed that they do not extend their tentacles when the organics are too high. (I may try to develop an anal retentive attitude about it. Let's see, Ron Shimek thinks its all about worms, Spanky thinks all the problems of the world can be solved by removing phosphates, and I think every tank would be beautiful if you maintained low levels of organics. See, the deal is I just bought a TOC (total organ carbon) analyzer and if you'll send me a sample of your tank water, for a "nominal fee" I'll tell you what you need to do to correct it!)