Help with random STN of SPS

[stancfii]

I've been pulling my hair out trying to figure out the root cause of STN I've been fighting since the summer. Alkalinity is stable at 8.0, calcium at 400, Mg 1360, nitrates may be detectable at 1 on occasion using Red Sea, phosphate 2ppb with Hanna ULR. Some SPS frags and colonies continue to grow at a slow rate, while others keep fighting STN... and they are in the same places they've always been. I've changed all RO filters, heater (it was old), new circulation pumps, test kits, everything I can think of other than my return pump (eheim) and skimmer pump (jebao). I dose ALK via Randy's recipe via BRS dosing pump, and Ca is Reef Fusion that I dose once or twice a week as I test for it. Prices like my green slimer go bottom up, but I have a red dragon that has started going top down. My only thoughts are bad salt or too many trace elements since the reef fusion has several in it. I switched to Reef Crystals earlier last year which may have been around the time this started, but I can't really remember. Before that I was using Fritz RPM and everything was growing well and colors were great, but not convinced the salt is the issue since some of the finest tanks I've seen use RC. Should I try a Triton test?? Lights are 3 Radiums and 2 VHO actinic, tank is standard 180. I run carbon through a reactor and rowaphos passively.

Thanks for the input.

 

[reefmutt]

I’d suggest raising nutrients a touch.
They are very low..
Could be the trace elements in the Fusion but they are usually in a concentration that is based on ca consumption so as long as ca isn’t high, trace elements added via Fusion shouldn’t be either.... theoretically speaking anyways!
Icp test wouldn’t hurt..
so you don’t add any aminos or anything else?

 

[Reiser]

po4 is to low and alk ist to high for ULN

 

[ClownNut]

rtn/stn from top down with all para in check
can be a sign of overdose on trace elements.

 

[Reiser]

po4 is to low and alk ist to high for ULN

with 0,02 po4 you dont need rowaphos. I have the same Problems with my Echinatas, Red Dragon und some deep Water Acros. The other SPS have no problems. The colour is most pale and not so clear with to low po4 at all SPS in my tank.

when i start dosing to much po4, change water, dose NO3, then i get more STN. because it was to much stress. Now I dose 1ml po4 per day on 1400l
Nitrates is 1 and po4 is 0,04

Skimmer not to wet

My Corals dont like carbon in an reactor. They have no polype expansion and my monti Reverse Sunset was grey with orange polyps when i have carbon in an Reactor.

iodine and strontium are important for stressed corals