If your putting phosban in the reactor it's no problem. Just make sure you rinse the phosban a bit to remove the dust. The phosban needs to be in a sock or it will just pour out.
I didn't say nitrites increased so I suspect you may be correct about nitrogen waste processing however some nitrogen processing bacteria has to get pumped about your system. Ammonia did increase to at least 5ppm that's why I cautioned it needed to be monitored. If you can run the UV long enough...
an in sump skimmer needs to be placed at the correct height in the water, too deep it overflows, too shallow it will not deposit skim. look at the manufacturer recommendations.
I just lost 6 fish to ich. I ended up adding a 36w UV to my 60 gal. tank running it at 250gph. Killed the ich but also kills beneficial bacteria so test daily and be ready to add a bacteria booster. When ammonia shows up in the tank pull out the UV. The remaining fish are healthy and the water...