Bleaching at the base. Pics

[samwheat]

I have just noticed about 6 of my corals are bleaching at the base. It starts on the very edge where it incrusts on the rock. This has me worried.
Can anyone give me some reasons this will happen? Its not a flow problem. Could be alk its a little low. Im still adjusting my reactor.
Alk was 7.4. Everything else tests fine. Sorry the pics are dark. If you look close you can see the blue stag the tort? and the red stag.

http://i27.photobucket.com/albums/c168/coralnut/Pg03.jpg

http://i27.photobucket.com/albums/c168/coralnut/PICT0002.jpg

http://i27.photobucket.com/albums/c168/coralnut/PICT0001.jpg

[samwheat]

Hmmmm

[mimosa]

Possibility of something eating or touching them at the base?

[tsutaoka]

i hate to say, but it sounds like sps eating flatworms.... i have a similar problem and still fighting the problem :(

[samwheat]

Thanks for the replies.
I dont think it fw I think my 6 line would take care of them if it were.
I figured someone here might know if alk swings of something would cause this. But it looks like people are to busy to reply.

[samwheat]

Wow, 160 views 2 replys. Now I know why I come here for help.

[easttn]

I don't think its bugs either. In the past 3-4 weeks have you been having abnormal swings in ph, alk, ca, or temp? When these fluctuate the coral stresses, you won't see the results for a week-month+ depending on how sever the swings are. Base recession is an indication of chemical swings imho. The bugs are an easy blame, but not root cause if simultaneously happening on numerous SPS.

[geno7]

What about phosphate loaded rock. Starts from the base up.

[easttn]

<a href=showthread.php?s=&postid=6549816#post6549816 target=_blank>Originally posted</a> by geno7
What about phosphate loaded rock. Starts from the base up.

Good point I've postulated about that in the past but no way to prove or refute I guess. I suspect the Ca reactor is Sam's problem.

geno7,

I'd love to see some reaction to that point, I've never had any luck.