Incessant cyano in established tank...

[Xirxes23]

I just got done reading an issue of coral magazine which said that cyano and dinoflagellates can take up non-combined nitrogen as food, and because of this even a reef tank should keep some small amount of nitrate in the water.

Tank has been up and running for about 3 years

I have been battling this cyano for a while now, and not sure what else i can cut out. We had been feeding heavily and adding home grown phyto for quite some time and the levels got out of hand, but over the last month i have cut out the fat and we are feeding very conservatively, no home grown phyto and decreased supplimentation all over, yet the cyano persists.

Even when fully cleared of cyano, the sandbed on our 90 becomes 50 percent covered in 2 days or so.

here are my levels:

Alk: 9.6 dKH
Ca: 400-410
Nitrate: 5-6ppm
Ammo: 0
Nitrite: 0
Temp: 76-78
PO4: less than .03
Mg: 1650 (due to addition of daily reef essentials, which i will be cutting back)

So, my skimmer is an oversized euroreef that fills about 30-50% of the cup a week, im skimming as wet as possible

Water changes are don't 20% weekly with NSW i check and adjust for PO4, NO3, alk and calcium before i put it in... never has NO3 higher than 3ppm.

I have some chemi-clean that i have used before on a different system, and im about at wits end and willing to use it if there are no other suggestions.



on a side note: my macroalgaes in the refugiem are not seeming to grow very fast, should i add iron, and if so at what rate?

Thanks for any advice ahead of time

 

[Kannin]

Your phosphates might not be reading accurately because the cyano my use them b4 they show up on the test. I beat cyano by shortening my photo period, adding flow, adding a phosphate reactor and draining off my melt from my thawed foods.

Have you considered the 3 day dark period? There's a pretty popular tread about it.

 

[Xirxes23]

having had experience with chemi clean, i think id rather take my chances with it, run 48 hrs no skimmer/carbon/phosban then skim and polyfiber the tank to get rid of it.

The devil you know is better than the devil you don't.

 

[revenant]

I had rampant cyano issues in my well established tank also... it started on my sand bed, then spread to my lower rocks.. it got pretty bad for a while.. what I finally had to do was blast the LR off with a turkey baster and clean off the top 1" of sand... stiring it very gently.. while doing agressive water changes.. like 20% twice a week for about 3 weeks.. I also added a lot more flow in the lower part of the tank ( with a Tunze a nanostream 6025 and Hydor Koralia #2 pump) so to try and keep the detritus suspended in water as much as possible... that seemed to do the trick, so I also opened up the rock structure finally so there was better flow between the rocks and it's way easier to blast them off... it was a lot of work but it seems to have paid off... and I learned a lot about proper flow. hope that helps some..

edit: I hear chemiclean works well, but you'll just get cyano again unless you treat the root cause of it.. I had a box of it standing by but I figure my way out of the problem without using it.. I have a slight trace of cyano left over from the sruge which I was thinking about zapping with chemiclean, now that my tank seems to be less of a breeding ground for it.

 

[Xirxes23]

with low nitrates and low phosphates (supposedly) i dont think that the cyano will come back... if it does ill have to see about adding some sandbed flow

 

[revenant]

it's not always caused by nitrates and phosphates you can detect with water testing kits.. it's the dead areas of your tank where detritus collects which makes it ripe for the bacteria to propagate.. well, that was certainly the case for me. my water looked good also and yet I still had the cyano.. it was very irritating.. anyways... try the chemiclean though, it's pretty easy and might do the trick for good.. good luck!

 

[moumda]

I've read that old metal halide bulbs might cause it. I let my bulbs go 18 monthes and I got it. Just changed by bulbs so I don't know if this will take care of it or not.

 

[revenant]

yep, old bulbs in general will help it grow better... I also noticed on my rocks, when I got some on the rocks, the algeas under the cyano died off and then a pocket of detritus would be left there, which would in turn fuel the cyano more.. kind of a vicious cycle. grrr. I had to do a lot of vacuuming.