Please Help: Macro Algae dying

[itreef]

In the past week my cheato in the fuge started dying. Previously it seemed to double every 2 weeks or so. I am even noticing that the coralline algae is dying or not growing. All corals look good with full extension and I do never had any other algae anywhere in the tank.

There have been no changes to the lights, but I did increase the time actinics are on from one hour to 2 hours during the middle of the day. (This cannot effect the refugium). I also did a 12 gal water change.

Parameters:
Salinity is 35
Alk 160
Ca 450
Mg 1500 I know this is high, can this be the cause of the problem
Nitrate undetectable
Phosphate I do not have a test but last meeting it was 0.03

I do water changes with RO/DI. Replace evaporation with calk. Dose 50ml of Randy Holmes' two part every day. Dose Kent Iron once a week. Skimmer is AquaC 150 that removes about 2 cups per week.

I am baffled, especially since everyone has more algae than they want I do not have any. (May be I should be happy about that .

Thanks all.

 

[Jim Tansey]

I don't know but have you read the recent threads on Mg and its effect on algae, you are on the high side.

Jim

 

[Reef55]

160 Alk??

 

[JohnK]

Not sure on the coralline slowing down, but IME with cheato if it gets overgrown it begins to slow and pretty much stop growing. Is the ref stuffed with the stuff? If so I'd suggest pulling a bunch out and see what happens.

 

[SteveDola]

iron can help with macros.

 

[itreef]

Jim Tansey
I did read about Mg and it may be a problem. I do not know if I should do a water change or just wait for Mg to go down on its own.


Reef55
Alk 160 ppm CaC03 = 3.21 meq/l = 9.0 dKH

jimmyj7090
I did pull most of it out. Now have a tiny amount left

SteveDola
I am adding Kent Iron, about 5ml per week.

Thanks all, but I still cannot figure this out.