Dying corals - can't figure out why

[klongo]

About two weeks ago my GSP stopped opening up, shortly thereafter my frogspawns stopped opening up. I've had my GSP stayed closed for a couple of days at a time before, but nothing like this and my frogspawn has always opened up beautifully for the past two years.

ALL of my parameters are stable at their normal values - I've checked them every three days since this started. I can't figure out why?

Temp is stable at 80
pH 7.9-8.0
Alk 10.2
Ca 470
Ammonia 0.1
nitrate <10
pO4 slightly high at 0.03

I've had a pO4 issue for about a year now, always about this level and I've never had any problems with corals before this! My T5 lights are about 7 months old.

I've changed nothing!

Any ideas are welcome......

 

[boxfishpooalot]

whats your salinity, and what do you use to measure it?

 

[klongo]

I use a refractometer and it's holding steady at 1.023

 

[boxfishpooalot]

when did you calibrate it last? Is it atc(automatic temp compensation)

 

[wayne in norway]

Water changes?

 

[klongo]

I change my water every 10-14 days - 20%. I've changed it once since this happened - with the same batch that I've used for the past 4 months. My refractomer does do automatic temperature compensation. It has been a while since I've calibrated, I'll try that tonight.

 

[Avi]

Even with very little apparent nitrates and or phosphates, you may have some traces of either or both in your reef. The tests may show low levels that appear inconsequential but there's enough to support a growth of micro-algae, who's presence keeps the test results low. That kind of micro-algae is often deadly to certain coral ...particularly any kind of star polyps, as it thinly coats the encrustation and suffocates it. It's often not even easy to see. Use a turkey baster to blast the surface of you affected coral. Increasing your overall waterflow may also help but water quality measures in general like have been suggested, plus making sure your skimmer is performing effectively and putting a phosphate reactor on the tank using something effective like Rowaphos may also be helpful.

 

[klongo]

Avi,

Thanks -- I increased my flow a few months ago by adding an eductor to my return and I do run Phosban. I change out the medium every three or so weeks. I skim wet and pull out lots of "junk" on a daily basis. I do have some micro algae growing on my sand which my cleaners can't seem to keep up with. I have this as an ongoing problem for almost two years. It's a brown dusty algae that I can't really identify, but it's not new and it hasn't gotten worse recently.

I'm going to blow off the GSP tonight and try moving the Frogspawn somewhere else in the tank for a bit.

 

[Avi]

<a href=showthread.php?s=&postid=8215960#post8215960 target=_blank>Originally posted</a> by katlongo
Avi,

I do have some micro algae growing on my sand which my cleaners can't seem to keep up with. I have this as an ongoing problem for almost two years. It's a brown dusty algae that I can't really identify, but it's not new and it hasn't gotten worse recently.

That sounds like it may likely be diatoms as opposed to algae even though there are some similarities, like the need for light. They thrive on silicates. There are test kits for silicates. It is frequently in the water from the sand substrates in many marine aquariums but it is also often brought in if the source of water for water changes (like tap water) contains the silicates. Using RO/DI water, in that event, would resolve the problem. I'm not certain about Phosban but I know that Rowaphos does remove silicates as well as phosphates.

 

[klongo]

I've had this ongoing issue almost since I set up this tank. It's the same filtered water source that I used for my 29 gallon tank for the two years previous. It's not RO/DI, but it worked for two years so I continued with it!

Thanks for the idea - I'll check out the silicates tonight also.