My Cyano Problem

[HumuhumuFan]

Hi, this is the problem I joined R2R to seek help on.

3 years ago I setup a 75g FOWLR tank. It has about 50 pounds of base rock in it, a few pieces of live rock and a shallow sand bed. Additionally I had an Eheim Classic Cannister. I worked in a pet store growing up 90s and jumped back into the hobby with my 1990s ideas. At the time it had a 3" Yellow Tang, a 4" Melanarus Wrasse and a 2.5" Rectangle Trigger (my avatar picture). The tank was running really well and I added a piece of live rock that must have had aiptasia. I really liked the aiptasia, there's just one, what could be the problem, right? Needless to say, it got to the point were all efforts to keep up with Aiptasia X, etc. were futile. I didn't think a filefish would work because of the trigger.

Long story short, I moved fish to QT, bleached all of my liverock and ran straight RO/DI water in the display tank for 2 weeks. I recycled the tank and moved the fish back. Unfortunately, my triggerfish died while in QT. Also, my tank grew a ton of cyano and green hair algae. At first it was purple cyano, but now it is bright green. The cyano and GHA is still growing strong 7 months later.

Tank Stats:
Filter - Eheim Classic with carbon, Purigen and Phosphate removal filter pad (not optimal I understand now but I got rid of all the ceramic bio media)
Flow: 2 Hydor Koralia 1150s
Light: ZooMed LED
Temp: 78 degrees
Ammonia: 0.0
Nitrite: 0.0
Nitrate: 0.0 (strange)
pH: 7.8 (a little low, but stable)
Specific Gravity: 1.025

For salt I use InstantOcean with my own RO/DI. I just changed the filters on it, tested at 0.0 TDS.

For livestock I still have the tang and the melanarus wrasse, plus a clean up crew of 6 blue legs hermits and 6 nassirius snails. The cleanup crew has only been in there for a week. I'm sure they'll help with the green hair algae but I doubt they will touch the cyano. Any ideas?

 

[HumuhumuFan]

I realized the timeline is a little confusing.

3 years, established tank.
Past winter, nuked tank because of aiptasia.
7 months ago, tank finished re-cycling, fish introduced back.
Present - still has tons of green hair algae and bright green cyano.

 

[Firemanreefkeeper]

Try brining up nitrates just a little. Chemiclean is another option ive used. Also hydrogen peroxide works too but it takes some time. There was a huge thread on here a while back on h2o2 dosing

 

[HumuhumuFan]

Interesting suggestions, thanks. Based on that I did some research and now I think I maybe I need to take the purigen out of the filter and allow things to get a little “dirty”.

I’m really starting to wonder if I should just get rid of the canister filter altogether.

 

[HumuhumuFan]

Here's a closeup of my cyano.

 

[HumuhumuFan]

Here's a more size appropriate shot of the GHA.

 

[Firemanreefkeeper]

Any coral in there? Maybe lights out for a couple of days. More of a cleanup crew. I also have a 75 gallon tank and had 55 blue leg hermits and 12 trocus snails. The hermits settled to about 40 or so. A last resort, try dino-x. It says it's for dinoflagellate but it does hair type algae too. I know it won't get rid of green cyano but you have to start somewhere.

 

[HumuhumuFan]

Any coral in there? Maybe lights out for a couple of days. More of a cleanup crew. I also have a 75 gallon tank and had 55 blue leg hermits and 12 trocus snails. The hermits settled to about 40 or so. A last resort, try dino-x. It says it's for dinoflagellate but it does hair type algae too. I know it won't get rid of green cyano but you have to start somewhere.

No corals. Just the wrasse, the tang and cleanup crew of about 10 hermits and 6 nassarius snails. I didn't want to go crazy on the cleanup crew since I do want to try another triggerfish at some point. Based on your previous suggestion about not having enough nitrates, I pulled the purigen out of the filter. We'll see how that goes. It looks gross but the fish are fat and happy and everything else is stable so no harm in letting it play out for a bit.