It has to be the water ???

[Agu]

One of my three tanks has had a persistant cyano problem. It's a 40 breeder that was originally set up as a prop tank. I blamed the problem on the 400w mh stimulating algae growth and gave up. After removing all the corals I shut down the lighting and let the tank sit, pretty much ignored it, and the tank completely cleared.

Three months ago I moved everything to a predrilled 40 breeder with 400 w of vho lighting intending to set up a biotope tank. DSB and very little live rock in the tank, but with a remote sump with a big skimmer(modified cpr sr6), 40# lr, and refugium. Parameters, ammonia, nitrite, nitrate, phosphate have never been detectable. pH 8.0 to 8.3, temp 80+- 1 degree, alk about 9 dKH, haven't checked ca in a while.

The cyano came back with a vengance :mad: . Per TRA the solution is aggressive skimming, so I've been using a skimmer more appropriate for a 100+ gal tank. Per Dr Ron the solution is to siphon it out and remove the nutrients feeding the cyano, so I've been doing 5 gal water changes every 4 to 5 days. The result, the cyano is worse than ever.

Finally, I connected my established 37 gallon tank to the same sump. This tank has been trouble and algae free for over three years. I figured the established biofilter would help reduce algae in the forty breeder (and it was part of my long term plan). Now this tank also has cyano :(.

I've come to the conclusion something is getting through my RO/DI unit that I can't test/measure. I've replaced the prefilter, carbon block, and DI resin. Output tests 2 ppm using a Hannah handheld tester.

Steps I'm going to take, 1) Stop doing water changes 2)Aggressive use of polyfilter, carbon, and phosphate sponge 3) Add a second DI cart to the purification system 4) all topoff with kalk 5) temporary use of sponge filters and a turkey baster to get the cyano into suspension and remove it.

First, is my assumption logical??? Could there be another factor I'm missing??

Second, any other steps I could take?? Or things I shouldn't do??

TIA,

A frustrated Reefer aka Agu

[Randy Holmes-Farley]

These types of questions are always tricky, but here goes....

You might try testing the source water before the RO/DI, for phosphates, if you haven't already. If there is a lot there, then some might be getting through an imperfect RO/DI. The second cartridge would help here.

Cyano is about the only thing in our reef tanks that can fix nitrogen from the atmosphere. I don't know how efficient that is relative to sucking up nitrate or ammonia from the water, but cutting off all nitrate might not eliminate it.

The plan that you have seems like a good one, and I'm not sure what else I'd do. When I had bad cyano years ago, better skimming helped then. I have some now, but not enough to worry about.

[Agu]

Randy,

My source water sucks, and then my local water utility adds polyphosphates at an obscene rate. I can find out the exact amount with some research, but it's way high. I'm in a position where water changes can actually be detrimental until I can super purify my source water. I've decided to also clean the RO cartridge with a goal of 0 ppm TDS

Nitrogen from the atmosphere, hmmmm. In Mn in the winter we're closed up pretty tight, could that be a contributing factor?

Agu

[Randy Holmes-Farley]

Agu:

<< Nitrogen from the atmosphere, hmmmm. In Mn in the winter we're closed up pretty tight, could that be a contributing factor?
>>

No, air is mostly N2 so tightness of the house won't matter.

With that info on the phosphates, I'd focus on that.

[SteveN]

Agu, I am sure you have tried it, but I have noticed increased circulation usually decreases/eliminates mine.

[Agu]

SteveN,

Tried increasing circulation with minimal success. In addition the only thing that changed in the second tank was shared water source. Everything else stayed the same, lighting, flow, inhabitants, etc.

FWIW, my local water utility adds polyphosphates at the rate of .5 mg/liter. So I've ordered more polyfilter and phosphate sponge plus I've setup a twp after the RO/DI to super purify my source water. Still can't get it below 2ppm so I'm going to try running the output through polyfilter and/or a phosphate sponge to see what happens.

Agu

[Randy Holmes-Farley]

Agu:

Is the 2 ppm value a TDS reading or a phosphate reading?

[Agu]

Just an update,

I've stopped water changes, am blowing the alga (I'm not sure my id was correct btw, from reading several descriptions it may be dinos) into suspension with a turkey baster, and I'm removing it with a fine net and sponge filter on a powerhead. The sponge is replaced at least once a day with a clean dry sponge. There's a sheet of polyfilter in the sump, all makeup water is kalk, and I've set the skimmer to remove a wet foam. This allows me to dose even more kalk into the system.

Obviously the problem has not been resolved in only a week, but there is a visible reduction in the infestation.

Btw, the 2 ppm was TDS.

Agu

[jck]

I've been watching this thread with some interest as I have a massive cyano problem that's been going on for about 4 months now.

When I originally set up my tank, I had a dino problem, but it seemed to go away once the tank matured a little. The cyano, however, came on after several months of perfect conditions and has refused to go away since then.

If it is dinos, I can tell you my experience. My original and makeup water were both 0 TDS so I couldn't blame the water. Everything other than the Southdown sand came over from an established system that had no serious algae problems. Reducing the photoperiod and manually removing it were the only ways I finally got ahead of the game.

Anyway, good luck.

btw - The stuff I had that people have since called dinos was a thick brown mat...rather fuzzy looking.