I have the same problems on my Hawkins Echinata, Turaki, Purple NaNa, Assuie Milli, My Unknowns, and my Purple Monster. JUST THE TIPS turn white. JUST LIKE YOUR PHOTOS.. I have yet to figure it out.. but i have come up with a few good ideas..
Everytime i seem to lose a fish and dont catch it when it passes away.. or i have a small amonia spike or mess with the sandbed.. this seems to go on.. So that is suspect #1.. amonia.. nitrites.. nitrates.. and then the newly formed/growing tips burn off.. becasue the ammonia eats them aways.. and they turn white.. BUT once i fix my water.. for some reason.. they grow with dark brown algea.. then the tips regrow over each other.. and are back to normal.. I actaully freaked out when i saw this thread becasue i have been tryign to seach for the reason now for a while.. i didnt see ANYONE with this problem.. BUT I DO HAVE THEM GROWING AND HEALING
Might be a phospahte thing.. SUSPECT #2.. whenever my phosphates have been getting a little too high.. too many fish... once again.. water change.. and phosban.. and a pinch of sugar (water change only).. gets it right back on track..
I also noticed that my alk drops from time to time.. SUSPECT #3 think i have my Calcium reactor setup wrong somehow.. i dont know.. ONCE AGAIN.. a water change.. levels back in check.. and poof.. eveyrone gets their color back and regrows their tips..
LAST .. but not least.. one night i saw one of these little White starfish.. (SUSPECT #4) sitting right on the tips of the coral.. muching away.. when the lights come on.. pure white.. BUT.. ive noticed.. the ONLY time they are on any coral.. is when they KNOW it is dying.. they clean the dying flesh off.. other than that.. they have not been back.. when they coral regrows and is doign good!
so.. SOMETHING in the water is off.. its not the electric.. not the calcium, no bacteria.. if any of those were the case it would still be happenning.. its not mag or ph..
i think i have it nailed somewhere between Phosphate, ammonia, nitrite, nitrate, and alk.. it is either a combination of a few bothering the newly formed tips and then maybe it is the white stars coming in to clean up?? I notice for the most part they eat off the glass. . but then i find them on the corals that sting each other and die off.. or the tips.. they like to clean up..
i dont know.. like i said.. my levels are pretty on target..
anyways.. sorry about your death.. i know it is frustrating.. if you would like someone to hold them and try to get them back.. i can help out or give it a shot.. ive held sps for a few people and brought them back.. up to you.. i know you dont know me.. but you can ask anyone i guess who knows me.. 10465 in the bronx, 347.614.1814
I can try anyways.. if you are interested.. BUT.. i have had the same problem.. same EXACT problem. and i came back from it.. so you can too!
just for info.. my levels when all that goes on are around
ph 8.2
alk 6.7-7.5
cal 430
mag 1300
amm .02
nitrite .05
nitrate .05
phos .003
when they start to heal and it doesnt happen anymore..
ph 8.2
amm 0
trate 0
trite 0
phos .001
alk 8-8.5
mag 1500
cal 500
im a pretty busy dude during the year.. so i dont have time to sit on the tank.. but i notice it happening and i know something is off.. but i normally get them to turn around.. and then they have they funny bumps where they start to grow over the dead part and the slime.. anyways.. i dont know if this helps at all.. hope it does.. but i get them to turn around..
but i would do what rick says.. maybe move the colonies and see what happens.. that way you know for sure what it is.. and that you start with process of elimination.. becasue this was making me bang my head up against the wall.. i also blast the tank with a water cahnge.. i dont do 10% i do close to 40-50% when i see it happen.. then i wait.. 3 or 4 days.. let the tank do its thing.. and hit it again with a 30% change.. and normally within a week or two.. everyone is back on track. good luck.. and if you need a place to try to get them back on track.. someone with the same issue.. give me a shout. thanks. marc 347.614.1814
marc