50 gal tank is 6 months old, SPS dominated.
Everything was going great then most of the SPS turned very pale 4 days ago and I've lost 10 of them since then.
sg - 1.025
cal - 450
mag - 1350
alk - 10.5 dkh
pH - 8.0
nitrate - 0 with API test kit, 10 ppm with Elos (consistently)
phosphate - 0.05...