Diatoms on SPS tips?
 

Have two frags in my tank that look like they have a small dusting of diatoms on the tips. It can not be blown off with a turkey baster and not sure if it's harming the corals. Showed up approx 2 days after a 20 % water change. I have no other signs of algae or diatoms in my tank and in fact I only have to clean the glass every week at this point.

Paramayers as of this morning during lights out:

Nitrate between 5-10 ppm
Phosphate .01 Hanna ULR
Calcium 420
Alk 7.3
Mag 1300


Here's a pic if you can make it out.

http://i1150.photobucket.com/albums/...921_122632.jpg

The reason algae is now going on the frag is because its dead.

There is no flesh left on that frag.

It's pink and has polyps below the tips pic just looks really washed out

Looks dead to me. Algae doesn't grow on live flesh

Tips look dead you can still see a pattern on the skin if you zoom in is it rr pip by chance?

Yeh it's PIP I cut off the tips to see if it recovers it's one of the ones that barley survived the bugs but obviously not out of the woods yet. Gave it a dip too and no pests so that's good news at least.

Well from past experience pip is one of the only rr pieces I've ever killed it never grew and looked identical to your piece in pic. I'm onto my second piece now hope I have better luck this round.

Yep I had the same experience , my pip died at the tip and the algae started to grow. It's still alive but has looked the same for months now with no change. It's still alive so I guess that's a good thing lol.

I've had just plain bad luck with all my higher end sps. My alk did creep up to 8.5 and I run biopellets so may have burnt the tips. Back down and stable at 7.3 since switching my brand of 2 part.

Funny I switched from JL soda ash to big reef depot soda ash and my Alk has never been more stable. Also my Ph now runs between 8.15 and 8.3 where with JL soda ash it was constantly dipping down to 7.8.

Really doubt that your alk going up that little bit did anything I have multiple time got mine up to 15 in the last year with no effects on the tank. Pip is just a hard piece to get growing Good luck Derek!