Is this ostreopsis? And plan of attack

[saltcats]

I'm pretty confident in my ID but I'd like confirmation - is this ostreopsis dinos? (And is that some cyano as well in the second pic?)

I moved everything from my 10 gallon tank to a new 50 gallon end of Feb - moved over all live rock, added additional dry rock and sand. My nutrients were bottomed out right at the start but I've been dosing and testing heavily to keep on top of that. Posted graphs below of my test results. I have phos on an automatic doser presently so I am pretty confident it isn't bottoming out at any point. I think I need to target nitrate a little higher?

Sounds like for ostreopsis I need to keep nutrients up, manual removal (including filter floss pads in the display that they'll gather on and I pull out each night?)... considering a UV as well. Anything I'm missing?
I'm running carbon passively at present, going to try to put together a DIY reactor soon to help the effectiveness.

Appreciate any help, my corals aren't very happy with me right now

 

[Reefer Matt]

It looks like it to me. A uv sterilizer worked every time in the cases I had it with three different tanks. I got the smaller hang on style from BRS.

 

[Uncle99]

It’s a numbers game.
Remove and replace filter when lights come on.
UV during lights out.
A light vacum through a tight filter sock,when lights on, put the water back.
As you say, nutrients in the range, a daily dose of bacteria and a daily dash of phyto.

 

[EricR]

Video under microscope is helpful -- consider posting to this huge thread:
Dinoflagellates

There are many threads on dinos but here's another:
Dinoflagellate Treatment

For ostreopsis, everything you said is what worked for me:
- Keeping nutrients from bottoming out (I dosed a ton of phosphate for a long time)
- Lots of manual removal, including pulling rocks and scrubbing in separate bing of saltwater
- UV running at night -- I went with cheapie Green Killing Machine 9W in 40 gallon tank and that seemed to work great for me

 

[saltcats]

Thanks everyone for the responses! I ended up finding an AquaUV 15W sterilizer secondhand so that's arriving tomorrow, probably a little overkill but I want them gone before my corals go!

Video under microscope is helpful -- consider posting to this huge thread:
Dinoflagellates

There are many threads on dinos but here's another:
Dinoflagellate Treatment

For ostreopsis, everything you said is what worked for me:
- Keeping nutrients from bottoming out (I dosed a ton of phosphate for a long time)
- Lots of manual removal, including pulling rocks and scrubbing in separate bing of saltwater
- UV running at night -- I went with cheapie Green Killing Machine 9W in 40 gallon tank and that seemed to work great for me

I have a video also that I didn't post, but I did notice the swimming pattern that was described (spinning with the pointy end inwards).
I've had dinos a few times before in my nano tank but this outbreak seems a lot worse... in the past I've just brought nutrients up to a safe level and they've resolved within a few days. My tank seems prone to getting dinos (I have always struggled with low nutrients and seems like any kind of disruption causes a flareup); I'm hoping to get things properly resolved and stabilized after this!

Any advice on pump size for this UV unit? I know the threads say 1-3 times tank volume per hour, although that's a lot lower than the suggested minimum for the unit... Would something like 300gph be okay? Puts me just above manufacturer's "minimum" flow rating but still not too fast. Pumps I'm looking at are adjustable anyway so I could dial it lower if I don't notice improvement.
Should I run the UV just at night or is 24/7 okay if temps don't get too high?

One more UV related question if you don't mind - I'm confused about how to set it up to pull from/return to the display. Probably overthinking this but - the pumps I'm looking at are the typical "return pump" type that sits on the bottom of the tank; this wouldn't work with a sandbed, would it? Do people mount them to the back somehow? Or am I looking at the wrong type of pump entirely?
Want to have everything ready to go when the UV shows up, thanks!

 

[saltcats]

UV sterilizer did an amazing job, dinos cleared up within about the first week, and corals started to open (and stayed open!) that hadn't since the slime started.

And now I have small cell amphidinium
I think my phosphate bottomed out or got close to it at some point; I didn't spot that my dosing container had run out.

I did also get very rapid growth of something like GHA after the ostreos departed; now it has a beautiful bubbly crown of SCA on top of it.