Browning of edges and tips

[Long Island Andy]

Hi
I have been keeping SPS for about a year and a half, in the past 3 months I have notices a browning on the tips where algae starts to grow. My levels are good .02 Phosphate (Hanna Checker) Nitrate 0 with Red Sea test kit. I do water changes every 10 days and maintain DKH (9) and Calcium (420-480) with and MRC reactor, I run GFO and have a a very active refugium. I run Radion lights. I have no algae growth in the tank. Does anyone have any idea what could be causing the browning.
Thanks
Andy

 

[machodik]

Yes , I also wish to know because that exactly happens to me too.

Cheers,

MD

 

[NaturalReef]

Looks like you had alk burn....any spikes you can account for?

 

[machodik]

No my alkaline are very steadily stable at 7.90 dkh

 

[reefmutt]

Hm.. This is a tough one.. Could be so many things..
I'd start with lowering your alk to between 7-8 and get more fish so that you can start getting a measurement for nitrate..
That's all I would do for starters.. Lower alk, raise n- try to keep everything else the same.
What salt do you use and how big are your wcs?

 

[jduck]

Tank is to clean for alk that high. 7.5-8dkh

 

[Long Island Andy]

I have uploaded a few pictures

I have uploaded a few pictures

Here are a few pictures