I think we're saying very similar things. I guess I use the term ULNS incorrectly.
My tank had constantly undetectable N and P with even A LOT of feeding. I fed 5x as much (my fish wouldn't even look at food anymore), dosed amino acids and also fed reef chili every single day. Still undetectable N and P. I ended up removing all sorts of filtration, including marinepure blocks and so on, nothing helped and I could never bring up N and P levels.
When I say I overfeed, this is what I did with my little tank:
- 1 whole cube of PE mysis a day
- 4x a day, AFS that fed three drum rotations of TDO Chromaboost Small pellets on the smallest AFS setting
- 5x the recommended reef chili dose
- 2x the recommended amino acids dose
- I had very slowly raised all those amounts over a few weeks.
Eventually I just dosed N/P straight to get those levels up since the above did nothing with the levels.
Keeping my sand/rocks pristine was probably less about trying to NOT feed, but more because I took great lengths to avoid hitchhikers. I QT'd, scrubbed snail shells, and even went with cleanly grown chaeto. Ultimately dinos made its way in (not surprised I guess, things are going to hitchhike regardless). Also, my filtration with the marinepure block may have been too aggressive.
I'm not sure how else I will be able to beat the dinos. You said I need to occupy surfaces. They are already covered with green algae (they're not white), but on top of that they're also covered in dinos.
Since dosing N/P to get them to acceptable levels is making dinos worse, I'm going to go the way of trying to outcompete with chaeto and NoPox. Though I'm pretty sure my chaeto will just die if I use NoPox since there will be close to zero N and P available... A simple system would be just feed regularly, use aminos to feed the corals, and dose NoPox to outcompete.
If I go the route of just defeating the dinos then running the tank as usual, I'm pretty sure the dinos will come back. My tank will not have the available N/P levels to sustain algae that will outcompete the dinos.