[nematode]

I took my 10 gallon Q tank that looked like (posted above) that was infected with "dinoflagelletes" actually Eudorina based on microscopy.

Only thing in the 10 g tank with a 10 g sump was some pieces of live rock and two small corals. I scrubbed everything I could and cleaned off the walls, and replaced 5 or 6 gallons of water doing that.
Then I added ~ 1 cup of algae- liquid that I had scrapped off of the sidewall of another one of my tanks. ~ 20 x 20 inches of algae junk collected on a razor blade cleaning the glass of my tanks.
I dumped that into the freshly cleaned tank,
I then (~ 10 of 14 days) added 1.5 ml 3 % h202 to the tank in the morning each day (that I did it).
The green algae has taken hold and the eudorina does not seem to be coming back as of yet.
In the three times I did complete changes before I never got growth of green algae (never added a bolus of green algae either)

(still looks pitiful, but much better)

Not sure what did it, H2O2 or the algae, but I think (hope) I am on the right track

ps I have a 20 gallon fish Q tank right next to it with a growing eudorina problem. I did not clean that one but have been adding 2.0 ml of h202 (3%) each day I have been dosing the 10 g and so far, the h202 had done nothing for the other tank.