Dinoflagellate ID

[Zakary2003]

I'm having a dino outbreak that keeps stubbornly coming back. I've raised my nutrients back up and have done some blackouts and reduced lighting, and they tend to disappear for a bit and come back after a few days to a few weeks. I recently added a UV sterilizer and that stopped the long stringy strands of dinos but they still cover the entire tank in brown/orange fuzz. I decided to take a sample with me to visit my former high-school and convinced my former biology teacher to let me borrow a microscope, and these are the pictures I have that look somewhat clear. As far as I can tell, it seems to be one species, but I'm not very good at IDing microorganisms based on the threads on this site.

In a sort of unrelated note, I saw a tiny invert under the microscope that looked kinda like a leach that was going around and devouring dinos by the dozen. You could see the dinos getting digested inside it's clear body. I didn't get any pictures, but it was super neat.

 

[SaltwaterScoop]

It looks like Ostreopsis to me, but I'm no expert. They are the most toxic but easily removed by an oversized UV unit in about 2 weeks. They usually appear as long strands in your tank so that's another clue.

• How big is your tank?
• How big is the UV sterilizer?
• How long have you been running your UV?

 

[Zakary2003]

It looks like Ostreopsis to me, but I'm no expert. They are the most toxic but easily removed by an oversized UV unit in about 2 weeks. They usually appear as long strands in your tank so that's another clue.

• How big is your tank?
• How big is the UV sterilizer?
• How long have you been running your UV?

The tank is a 20 gallon AIO. The UV light is 50 watts and is housed in the back middle filtration chamber. The UV has been running for 11 days.

 

[SaltwaterScoop]

The tank is a 20 gallon AIO. The UV light is 50 watts and is housed in the back middle filtration chamber. The UV has been running for 11 days.

That wattage for your tank size should be perfect. From what I've read, too high of flow rate through the UV can cause performance issues because dinos need more contact time with the UV. I'd give it a few more days and see how things look. You also might notice new algaes starting to take hold so don't be discouraged by that because that's a good sign! The only way to know if you've eliminated the dinos for sure is to check another microscope sample.