Okay, so water change complete (50%).I would do a water change to try to lower nitrate but 0 phosphate isnt great either. Putting the dendro out of any light and in full shade will help as it is nonphotosynthetic, while the algae needs the light.
Here is what I'm working with:
Salinity: 1.025
Temperature: 79.8F
pH: 8.0-8.2 (Hanna Checker on order)
Ammonia: Between 0 & <0.15 (I STINK at reading these dang Salifert tests)
Nitrate: ~10ppm (API for now, Hanna Checker next)
Phosphate: Just above 0 if not 0 (API for now, Hanna Checker next)
Calcium: ~420ppm (API, Hanna Checker later)
KH: 8dKH (API)