I'll be curious to see if you can knock them down without UV. Someone around here also said they used 1 micron filter socks to trap dinos. Another used a diatom filter. The concept being Remove, versus Irradiate.Tested my water again to ensure nutrients stay high. They do not seem to have budged from yesterday. I can only assume that reducing the photo period on my fuge had something to do with that.
I "swept" the sand this morning to get the dinos into the water column. This also lets me see how fast they grow back etc. Although I'm only about 2 hours into my 6 hour lighting cycle for the day things are looking PRETTY good. I will post a picture later tonight as we get closer to the end of the 6 hours.
Your lighting modifications should inhibit the dino reproduction... but these might also limit the ability to grow competitive film algae. I don't know.
Stick with it; keep us informed.