opinions will range strongly on that approach. my own is set by the details in the pics and the coral growth. if that was my tank id not dose it with chems, chemi clean or anything.
I also wouldn't change nutrient params, Id act independently on the unidentified target. it is clearly not an anchored invader and due to that my course of action would be twofold
1. get a uv meant for a pond, not an aquarium
2. take time to hand siphon, using the end of the hose as a scraping tool in some way, all of the material out. it should take hours of work and a few good water change runs to get it all out by hand
hook up the uv only on the clean condition tank.
return uv in 25 days if not happy, check for return options before buying. This works well, we've already been doing it a while and many opt to keep the uv
the reason to do a pond one is because you can't over do it, but can under do. An 80 gallon tank wont overheat, I used a ten thousand gallon pond sterilizer on my planted 75 gallon tank for a decade straight. my grandmother didn't want it on her koi pond so it got the kick down to the planted tank as a blue green cyano cheat, and man did it work
cleaned up all gha too all via cheating. it didn't remove gha off the rocks, I did. it was installed on the clean condition tank, then things just stayed that way.
You have an obligate hitchhiker invader, that's atypical or we'd see it in ten thousand pico reefs posted constantly. that means once you burn it out, if the system works, you can take the uv offline eventually and the DNA that was burned out cannot get back in until direct import happens again. Im saying that doesn't look to be a typical invader for reefs
the zeovit system temporarily boosting competing heterotrophic bacteria in the water/substrate also isn't a surprise, zeovit is atypical reefing that involves strict nutrient alteration away from the norm. not sure of cause so far.
