Your thoughts?

[2002RamAir]

I've been having issues with keeping sps corals and can't figure it out. Everytime I get one they manage to live for about 3 days then they lose their skin. I have LPS corals doing just fine and can't figure it out. Any help would be great.
Tank
0 nitrate
0 nitrite
0 phos
0 ammonia
PH roughly 7.9-8.2 throughout the day
Salinity 34.8-35
Temp 78.6-78.9
Alk 8.5
Calc 470
Mg 1350
Weekly 7.5 gallon water change
Tank 54x30x24
Sump 40x18x18
Lighting 3 gen 2 radions
Power heads 2 vortech mp40 on reef mode
2 tunze in rear corners on pulse.

Thanks

 

[frog.pauley]

How old is your tank? The reason I ask is the rock still looks clean. Looks very similar to my marco rocks, and mine stayed that way for over a year. I had the same issue when I first tried SPS. I am on day three of my second try another year later. I think my reason for the necrosis was chasing numbers with 2-part and the tank just wasnt ready to be that solid. How much Alk swing are you getting over 24 hours?

 

[2002RamAir]

My tank crashed and had to redo everything. It is on its 4th month now. I figured everything would be good as my carpet nem is doing great and I'm showing signs of coralline growth.

 

[2002RamAir]

I'll do a couple tests through out the day tomorrow for alk. I'll try to get a test every 6 hours with my Hanna checker and another with salifert

 

[sprite]

In my experience, Zero nitrate and zero phosphate with alk over 8 dhk gave me stn. Now I try to keep it about 7.5-7.7 and all my stn problems went away.. Maybe something to look into?

 

[frog.pauley]

My S.Gigantea has faired pretty well even when SPS went into STN and RTN. Hoping I have better luck this time as well. I am reading close to zero nitrate(API) and my alk is stable at 8.4 currently.