Coral polyps getting stringy?

[aastretch64]

All of my lps coral are getting stringy and thinned out?

Alk: 10
Mag: 1400
Cal: 480
Phos: undetectable
Nitrate: undetectable
Temp: 79

Alex

 

[BLKTANG]

Whats your PH,& SG?

 

[aastretch64]

SG: 1.026
pH: 8.0

 

[cbrownfish]

Either allelopathy or water quality. Have you calibrated your device for measuring SG? LPS resent high salinity. Have any toxic chemicals, cleaning solutions, bug spray or similar, been near the tank lately?