My Two Cents......
A) find a microscope.... If you have large quantities of independent moving organisms..... Then you have DINOs.
B) I did everything..... And nothing seemed to work. Blackouts, PH, hydrogenperoxide, DinoX.....nothing worked.
C) I went dirty....fed fish like crazy.... Went high on nitrates and phosphates to promote green algae to grow and out compete DINOs. This was a suggestion I found for a guy in Germany who posted a picture of what I was battling and said these buggers like ULN systems...and thrived off of photosynthesis...
D) change lighting to remove blue or lessen it significantly. Go to more natural sun light...easy to do with LEDs. This was a suggestion of Matt at ShoTank. I like a lot more blue and Matt suggested that red organisms might like that spectrum more... See point above...
E) siphon out what you can
F) do not do water changes as this will feed DINOs.
This worked for me. I am battling some cyno now...and also trying to get nitrates and phosphates in control. But last several months and microscopic surveys....have not found DINOs. The single best way to tell DINOs is a microscope. Go on FleaBay and buy one for cheap. That is what I did. You will quickly be able to detect DINOs.
One last point I will make....all tanks have DINOs. There are thousands of different types... Different varieties live in all of our tanks. It is a few varieties that wreak havoc..when they find the ideal environment to live....and then you get an explosion. I am not sure you will eliminate them entirely...or even want to.
Good luck. I know they suck. If you are patient...you can beat them.....but it can take a while.