Are these Diatoms? If so how would you eradicate them?

[WRXTerror]

I have a reef tank that's been established for over a year now. Recently i have had an outbreak of what I believe are diatoms. I have been doing weekly 50% water changes, manual removal, and also tried using Seachem Phosguard. Within a day of a major cleaning they are back, within 3 days it's back to where it was. I have a 25 gal lagoon, ai prime hd light, IM skimmer, and ATO. My parameters have been good, and I feed lightly. i use IO reef crystals for my salt. Am I right that these are diatoms? If so does anyone have any suggestions for eradication? Thanks!

 

[JustinSmi86]

Looks like Cyano to me. Is it like a mat or dusty?

 

[Ron Reefman]

It's kind of hard to say (for me) based on those photos. The first two look like dinoflagellates. The third photo looks like cyano bacteria bloom. if it's stringy and snot like that come apart easily when disturbed (say with a fine fish net); then I believe it's probably dinoflagellates. They can be very difficult to get rid of and although I've had a couple infestations of them over the years, I'm not the guy to tell you how to get rid of them.

You probably could use help from a few members of the #reefsquad who have more experience with nuisance algae.

 

[Flippers4pups]

I would have to agree that it looks like dinoflagellates.

What is your water parameters currently?

 

[saltyhog]

As @Flippers4pups said! Specifically what are your NO3 and PO4 levels? Do you have access to a microscope? A video of the mat under the microscopic would allow absolute confirmation of which it is.

If it is dinos, Phosguard will actually make it worse, especially if your PO4 is very low.

 

[dwest]

I agree with others. I would definitely check under a microscope. I bet you would see both dinos and cyano. I would check both nitrates and phosphates and make sure neither are zero. I recommend the Hanna ulr phosphorous checker for phosphates.

 

[WRXTerror]

It is easily broken up and stringy. I bought the API kit and it reads nothing on those. I am ordering hanna and better tests today. I've changed nothing for months with the chemistry. Only change is a new fish, frogspawn, and zoa's. All of them were qt for 6 weeks. I have read here that some people have success with a blackout, might try that next week. This week doing daily manual removal.

 

[WRXTerror]

Also I don't have access to microscope, but will look under a cheap 60x hand scope I got.

 

[dwest]

Also I don't have access to microscope, but will look under a cheap 60x hand scope I got.

Amazingly, this $11 microscope works well enough for me.

 

[APX90]

I had a bad dino outbreak in my first tank, i blacked it out for 3 days twice and it came right back when the lights came back on. I eventually got rid of it by removing bio media, dosing 1ml/1gal of hydrogen peroxide and using Vibrant. i blacked the tank out 3 days, dosing peroxide on the black out days to weaken it, then dosed vibrant and fed heavy for about a week.