Hello Reef2Reef! I have had quite the conundrum lately and I am hoping to possibly find my answer here. LONG READ, PICTURE HEAVY! A little about my system: Tank: Elos 70, 55 gallon display, roughly 70 gallon total water volume Flow: Mp40 (reefcrest 60%) and RW-8 (50% random mode) Ehime 1260 return pump Lighting: two xr15 pros with wide angle lenses running coral labs SPS AB+ schedule at 70% Filtration: SWC 160 cone skimmer, refugium with chaeto Tank paramaters ALK: 9.0 DKH CALC: 450 MAG: 1360 Temp: 78 Dosing is done automatically VIA BRS dosing pumps through my apex with ESV 2 part. Alk and calc are checked weekly, mag once a month. Salinity: 1.025 (calibrated refractometer) Never fluctuates via auto top off Phosphate: 0.02 (Hannah) Nitrate: not tested Tank inhabitants Pair of clownfish Kole Tang One spot foxface Mystery wrasse Starry Blenny Misc snails and hermits Weekly maintenance 10% water change (Red sea coral pro) Weekly dosing of Acro power The Problem The tank has been up for close to a year now an up untill about 3 months ago everything was doing stellar, I was having excellent growth, polyp extension and color on all my SPS, I would get a frag from a friend, dip it, and throw it in my tank and I would start to see growth within a few days. Coraline was a borderline nuisance and I was scraping it off the glass DAILY. Over the course of the past 3 months things have begun to show some issues, SPS that were previously beyond fuzzy with PE started to recede and lose color. They wouldn't quite die, and would very slowly keep encrusting, but never seemed to bounce back. For instance: Red planet, previously a giant fuzzball: No namer Before picture: After: Here are closeup pictures I took of this coral to check for bugs: http://imgur.com/a/fi4M4 Other things losing skin/ no PE: Pac Man: Myagi tort, losing skin from base up, no PE: Before: Pearlberry, no PE lost the main part of it, cut it off to stop STN, base still alive: Purple Stylo: no growth in months, STN on bottom: In this time frame I also lost a very large colony of bird of paradise, it seemed to begin to lose its polyps and turned into a skeleton slowly over the course of a month. I also lost several other nice reef raft pieces that were given to me from a friend within a week of getting them, when I received them they had crazy PE while even in the container, and had great PE for about a day in my tank before losing all PE and then slowly melting over the course of a week. All these pieces are scattered across my tank and not located in one spot either. I still have other acros and SPS in my tank that seem to be doing just fine with fantastic PE and color but I have noticed their growth has slowed to a crawl. Coraline has also come to a standstill, and am noticing it actually receding in some places, as if it's being eaten away by something. Things that have changed in the tank since this all has started: Removal of sandbed, I had a VERY shallow sand bed of a heavy grain that I slowly removed over the course of 2 months during water changes. Switched the radion lenses from narrow to wide angle, I upped my lights output by 10% to compensate for the loss of power, I got an overall better spread with the lights, so I cant imagine it was a huge shock. If there is any other information I can provide please let me know, my friends in the hobby and local reef club seem to be at a loss so I am hoping the experts here on R2R can possibly shed some light on this mystery!