SPS trouble

[ROCKMAN_1]

Current system info.

90 gal tank with 30gal sump, 100 LB's live rock and a 3-4 sand bed. Tank has been up and running for 3 yrs now with minimal issues. I have not made any changes lately.

Fish: 2 med tangs, 2 med clown fish and 2 damsels.
Dose BRS 2 part on automated pumps.

Parameters:
Calcium 500
Mag 1290
Phosphate undetectable
Nitrates undetectable
Alk 8

So here is the problem. A few of my SPS colonies/ frags have started to die off in part of the SPS (some are the tips and the birds nest is random). I don't know what is happening. I cant see any pests of any kind either. Any suggestions would be great.

 

[ROCKMAN_1]

Any help/ thoughts are welcomed.

 

[Alex T.]

Do you run carbon? I see a lot of softies in the background. If you can rule out the usual (pests, spikes in alkalinity or phosphate levels) then it may be allelopathy from chemical warfare going on between your softees and sps.

 

[karsco]

Rockman, are you dosing any other products, zeovit, vodka etc.???

 

[hobogato]

i know this sounds basic, but what about your salinity? i have had issues like this because of low salinity caused by an out of calibration refractometer before.

 

[ROCKMAN_1]

Do you run carbon? I see a lot of softies in the background. If you can rule out the usual (pests, spikes in alkalinity or phosphate levels) then it may be allelopathy from chemical warfare going on between your softees and sps.

I don't run carbon on a regular basis. I did recently put about 2 cups in a mesh bag and tossed it in the sump due to my issue.

I have a very full tank mixture of softies and hard corals. If this is allelopathy, how can I prevent the process?

 

[ROCKMAN_1]

Rockman, are you dosing any other products, zeovit, vodka etc.???

I use to dose AA approximately 1 or 2 times a week and stopped about a month ago. Maybe this is the cause of my issues? could my SPS be hungry?

 

[preef]

Have you changed anything else that you may not be considering. Mixing container, salt, RODI filter, bulbs, light cycle, etc...? How long has this been going on? Any problems maintaining pH now that the weather is cooler and the windows are closed more?

 

[ROCKMAN_1]

i know this sounds basic, but what about your salinity? i have had issues like this because of low salinity caused by an out of calibration refractometer before.

I checked my salinity with my hydrometer and it was at .25 compared to my refractometer at .26

 

[Dustin1300]

Salinity should be good. What about temperature? Change in light bulbs/cycle/etc???

 

[ROCKMAN_1]

Have you changed anything else that you may not be considering. Mixing container, salt, RODI filter, bulbs, light cycle, etc...? How long has this been going on? Any problems maintaining pH now that the weather is cooler and the windows are closed more?

Mixing container is the same.
Salt is the same.
RODI replaced about 2-1/2 months ago.
light is the same (however the bulbs are approaching 1 yr old)
This started about three weeks ago and now seems to be stabilizing.
PH is stable.

 

[ROCKMAN_1]

Anybody think of anything else?