Dinoflagellates growing in frag tank

[arkodios]

I work at an LFS with an 80-gallon frag tank system. It has a few fish but it is a very light stock. It has coral frags resting on egg-crate and I believe it is lit using AI Prime 16HDs. There is a reddish, snotty, bubbly slime growing all over the egg-crate and even on some coral. I do not believe it is cyanobacteria because it is present even right in front of the powerheads (I have heard cyano does not grow in areas with high flow), and also, as per this post, it likely isn't cyanobacteria because after collecting a sample, shaking it up to mostly break it apart, and then filtering it through a paper towel into a cup, the slime formed into big pieces again within 30 minutes at normal room lighting.

The issue is, I have mostly heard that dinos grow as a result of (or correlated with) 0 phosphates and/or nitrates. I did both tests and the system has over 1 ppm phosphate and 20 ppm+ nitrates, we unplugged the skimmer anyways to let some nutrients rise and nothing changed. At the time of my tests, the salinity was at 40 ppt/1.031 sg-- I do not know if salinity affects their growth rate but we have lowered it down to 35 ppt/1.026 and the dinos are still there.

We are considering removing all the corals and letting the egg crate soak in freshwater to kill the slime, then doing a freshwater dip on the corals to do the same. I talked to my boss about leaving the light off for 2 days and installing a UV filter to see if that would do anything-- she said they would do that but I can't confirm. If they did do it, nothing changed. We might even dose the tank with MicroBacter7 but if that is the right course of action. Any suggestions would be appreciated.

 

[Woodyman]

I'd first post some photos preferably some microscope photos as well.

This way someone can get a positive ID on what your dealing with and recommend a proper treatment method.

 

[arkodios]

I don't have access to a microscope at the moment (I can try seeing if my science teacher will let me use his), but I do have some photos. They aren't the best due to them being on egg-crate and the lighting. When out of the blue light they look more brown than red.