Possible bleaching

[tripwater]

I hope this is the appropriate place to post this. Let me start off by saying my tank, the lighting, water flow and temp has been the same for over 6 months. I have a select few polyps and clove polyps shriveling up and losing color.


My brown polyps for well over a year have been healthy and extended and almost always open during the day. The clove polyps are spreading rapidly and doing well. But the past 2 weeks I noticed a couple of small sections that have started shriveling and going pale. All of my brown polyps are open but not extended, kind of still pulled in. The color around the edges going to white and in some cases the green mouth is now white.

I took out various pieces and dipped them in reef deep, an iodine solution. I have no idea what is causing this. They are under MH 500w lighting and according to my test kits, my salinity is 1.024, ph 8.2-8.4, nitrates 0, phosphates 0 etc. Temp is about 78.

I honestly find it hard to believe that my nitrates and phosphates are 0. They have never been at 0 so I wonder if my test kits are bad. Same kits I have used for the past 6 months. I have 2 kits and both show same results.

The rest of my tank is doing fine. It is a 55 gal tank.

Here are a couple of shots to show what they were like and then where things are now

Thank you for any help with this

A healthy pic of my cloves
http://farm3.static.flickr.com/2701/4445718782_d59c0e5172_o.jpg

Another section that is dying
http://farm3.static.flickr.com/2717/4444945849_ddf5785651_o.jpg

What my polyps used to look like
http://farm5.static.flickr.com/4007/4445718760_1ef6390894_o.jpg

what they look like now
http://farm3.static.flickr.com/2801/4445718814_6802b9509a_o.jpg
http://farm3.static.flickr.com/2700/4445718868_85d41382a9_o.jpg

It has been this way for almost 2 weeks.

[HighlandReefer]

It can be difficult to determine what is causing your problem. Some possibilites:

Alk is below 7.0 dKH and/or calcium is below 380 ppm.

Magnesium is very low, below 1285 ppm.

Your salinity can be lower (or higher) than you think if you are not using a properly calibrate refractometer.

Sudden increases in lighting or just starting to use GAC (or possibly increasing the amount too fast).

Your tank heavy metal concentrations (like copper) can be too high for various reasons like supplementing micro-nutrients or increasing mag level too much.

Too much carbon dosing can lead to problems (like vodka, sugar or vinegar).

Increasing your alk level too much has caused problems.

The list goes on. :(

[sedor]

My first guess would be NO3 or PO4 problems, even though the tank is showing 0. Are you noticing a lot of algae growth or anything else strange about the system?

[tripwater]

My first guess would be NO3 or PO4 problems, even though the tank is showing 0. Are you noticing a lot of algae growth or anything else strange about the system?

Honestly I don't see any access algae growth. One thing I did notice is that my coraline is starting to bleach as well. I have been ( for quite a while ) dosing my tank with purple up and occasionally 8-10 drops of iodine supplement. I ran out of my calcium test kit and never owned an iodine test kit and wonder if this is a result of a possible high levels of one of these. The thing I don't get is why it is only targeting a few corals. just a small portion of the cloves and then the rest still look like that first picture, healthy. All of my button polyps are this way however. But I have mushroom anemones, colt coral, galaxia, hammer coral, frog spawn, candy coral and all doing great.

I have since stopped putting anything in my tank for supplement. over the past 2 weeks I have done 3, 10% water changes and no longer adding anything else to see if it fixes itself.

Thanks for the replies

[tripwater]

and HighlandReefer, I know what you mean. I expected a list of possibilities. I have not calibrated my refractometer in a long time. I will do that today to be sure I am not getting the wrong readings.