Your numbers are good except for the potassium (Kh). I think it is an aberration. If phos is low, I would not dose anything like acabgd said. Is the CurrentUSA light for reef or the freshwater one? It should be ok for softies.
Hi,
1) you should stop using seachem marine buffer 8.3. That's the reason your dkh is so high.
2) do a water change 25%.
3) try to get better test kits (salifert) are cheap.
4) if you could post photos of your tank and sump.
5) get into water change every week until you system is stable, you need to get into a routine.