I've been running the L2 UAS on a 40 breeder with a ton of LR, 3 angels, 1 big tang (police have been knocking), a small clown, and a pistol shrimp/goby pair for about a month now. In that time, feeding no more than about 1.5 to 2 cubes every other day, algae growth has been good on the scrubber, but nitrates and phosphates have spike dramatically. I just did a 15g PWC (which is about 50% of the actual water volume) and API nitrate still shows over 40ppm, probably closer to 60. Before the PWC it was off the scale red (>100, IMO). I didn't even bother to check P before the PWC because I didn't want to waste a reagent.
Had to pull some corals out into a QT 10g tank. One RTNd in a few days and the other started to.