Burnt Tips

[Reef Pets]

Typically I turn off all of the flow in my tanks once a day to inspect the coral just to make sure everything is doing OK. Well today I noticed that many of my SPS in one tank have "burnt tips". Meaning, that many of the tips have lost flesh and the white is barely showing. So of course I checked all of the perameters and done a 20 percent water change. Everything checked out just fine before and after the water change.
This same thing happened to me about a year ago and I could never figure out the problem. Within about 3 weeks all of the tips grew back flesh and were in perfect condition again.
Any idea what may cause this?

 

[Reef Monkey]

New lights/light bulbs?

 

[AquaWorldPSC]

Alkalinity burn, What's it at?

 

[returnofsid]

High Alk, Low Mg or lighting too intense would be my guess.

 

[Reef Pets]

I have not changed the lighting and have always used the same bulb, Ushio's. The bulbs are about 4 months old. Mag is at 1200 and DKH is at 8. None of the levels have been changed or spiked and some of the acros have been in the same system for over a year and some of the acros have been in the system for just a couple of months. But, 99 percent of them have burnt tips. The first think I though was ALK burn so I tested with two different kits and got the same results...

 

[Reef Pets]

I just tested the ALK again and I was wrong, the dkh is 9.
The only thing I have done differently is Vitamin C dosing. I have been doing it for about a week now. The water volume is about 110 gallons and I have been adding 1/4 teaspoon of Vitamin C two times a day, once with the lights out and once with the lights on.
The other system that I have seems to have emproved in only a week from the Vitamin C dosing.

 

[DJreefer]

How do you maintain your alkalinity? Dosing pump? ATO? Manually?

If I had to guess, I'd wager your Alk dropped below NSW levels [sub 7dkh] for a short time. That's all it takes to really thin SPS tissue and cause tissue loss on the tips.

HTH