Feisty Green Star Polyps

[lunatank21]

Long time lurker, first time poster!

Specs:
65 Gallon tank
AquaC Remora Pro
Current Nova Extreme 6x39 T5s
Maxijet 1200 with mod kit (allegedly 2400gph), Koralia 2
~90lbs of live rock
Ph - 8.4
Salinity - 1.025
Calcium - ~490
Nitrate - 0
Temp - 79
De-ionized water source

Live stock:
3 clowns, yellow tang, blue hippo tang, 3 pepperment shrimp, some crabs and snails

Coral:
Toadstool Mushroom Leather
Derasa Clam
Candy cane coral
Bubble Coral
Green star polyps
Pink nephthya (not exactly sure what kind)

The tank has been up and running for about 4 years, I purchased the green star polyps about 1 year ago from the LFS -- nearly a frag about the size of a quarter that 2x-3x its size over that time period. However, the polyps slowly began retracting in small sections about a month ago and have basically been hiding ever since. The mat is still hard, light purple on top and dark purple on bottom. Placement is 6 inches of bottom in front right corner of tank, nephthya 6-7 inches away. I noticed that there was some detrius build up on the mat so i used a soft tooth brush to clean it off and increased the flow to that area about 3 days ago. Looking for any suggestions or empathizing stories to make me feel better. Thanks again in advance, go bucks!

[Dragonist]

use a turkey baster to get the detritus off...of point a power head @ it brushing can result in damaging the polyps.

[lunatank21]

I will do that, but what are the chances that it is dead?

[REEFIN'ROB]

ph and calcium look a bit high. i've seen star polyps close for a long time and suddenly come back. they and euphyllia are usually some of the first corals to close if there is a water quality issue. do you dose anything? have dosed anything new? how often do you do water changes?

[lunatank21]

I dose with B-ionic a couple times a week (alkalinity and calcium) - i have peared back the calcium lately to hopefully reduce to the 400-440 range, maybe i will do the same on the buffer. Top off the tank weekly but actual 5%-10% changes are done probably every other month at most. Very frustrating to see the clam thriving but the GSP struggling, starting to think i took the "can't be killed" reputation to the brink.

[Salty O'Shen]

nice to have you posting on TRT!!

i had the same problem with one of a couple frags of GSP i have in my tank about 1 month ago. i blew it off with my power head and noticed a smalle brittle star that was living in among the polyps. i moved it to a different rock and they came back out a day later. so, maybe you have a critter that's bothering them. they will retract if a snail, hermit crab or other critter is using them for a hideout. may not be your situtation, but something to check.