Green cyano in Ultra-Low nutrient system?

[Oimate84]

I need some help in getting rid of some green cyanobacteria growing in my sps dominant tank. It started about 3-4 months ago after experimenting with vodka dosing, I must have gone overboard with it and suddenly this green cyano started showing. Since then ive stopped dosing vodka, done many water changes, changed my t5 bulbs, changed DI cartridge, turned fuge light on a 24/7 schedule, everything and its still there! Im starting to dose microbacter7 now as a friend suggested it might help reducing any organics thats fueling the cyano, but i only started dosing this about 2 weeks ago so its still too soon to tell. Any help would be appreciated to ridding this problem. I also dont want to dose any chemi-clean or the like to just mask the problem.

Heres my water parameters:
Phos- 0.02 (Hanna Photometer)
pH- 8.1-8.3
Calcium- 420
Alk - 9 DKH
Nitrate- <5
Salinity- 1.025
Magnesium - 1300
TDS out RO/DI - 0

 

[beaslbob]

Kill the lights on the display for a few days to kill off the green cyano.

 

[AlexStinson]

I find it hard to imagine that it would grow in a truley ULN system

but otherwise I would suggest using some chemiclean, it always works great for us.

 

[gilmour01]

be sure you have adequate flow as well

 

[Oimate84]

In a 125gal tank, I have 2x Tunze 6100's + Closedloop w/sequence 4200gph pump and my return, its plenty of flow everywhere but this cyano doesnt seem to be phased by it. I think ill try lights out for 2 days, dont wanna go more then 2 with all the SPS in the system....

And I have heard about some stories with overdosing vodka in ULN system causing this specific green cyano outbreak, so all other factors eliminated I think the vodka is what started it.

 

[gilmour01]

just out of curiosity (b/c i also dose it), how much vodka did you dose or were you dosing?

 

[Oimate84]

At one point i was dosing 2ml a day. I didnt do the gradual intro dose very long, maybe about a 1.5weeks before i went overboard with it.

 

[beaslbob]

Did you have any vodka left over?

If so I have a much better use for it. :bigsmile:

 

[H@rry]

Turn all the lights off for 3 days. Only ambient lighting. On the 4th day turn on only the actinics. On day 5 turn all the lights back on. This should be a major improvement. You may have to repeat this in 2 or 3 weeks but it has always worked for me.

I don't necessary buy the flow thing. I have had cyano in the overflow box, the highest flow area of the tank.