Mushroom condition appears to be worsening

[MiniDevil]

Everywhere I have read says that mushroom corals are pretty impossible to kill, and are great for beginners, etc. I have Green, Blue (purple), and Red mushrooms. All three have made little baby mushrooms and all seemed to be going perfect. I got them from 20,000k metal halide lighting, and that's what they are in now, toward the bottom of the tank. They've always enjoyed the lighting from what I've seen, and at one point were spread out the size of a silver eagle (1.5" diameter?). All of the mushrooms are great except the original mother red mushroom, whose condition seems to be steadily declining. It's shrunk over the past couple months to be no bigger than a dime, and has a lot of gray color to it, especially in the center. Is there something I can check for, maybe some type of parasite or something?

Tank specifications:
75 gallon, 30 gallon sump, 93 gallons actual water capacity
110lbs liverock (30lbs tonga and 80lbs fiji)
Bubble Magus NAC 5.5 Skimmer
Bulk Reef Supply Dual Media Reactor (Running GFO + Carbon)
1300 GPH return pump, 1600gph wavemaker, 800gph wavemaker
Chaetomorpha in sump

Tank chemistry:
1.0245 reading on refractometer
Ammonia - No reading (API)
Nitrite - No reading (API)
Nitrate - No reading (API)
Copper - No reading (API)
Phosphate - 0.02ppm (Hanna Phosphate Checker)
Calcium - 430 (API)
dKH - 13 (API)
PH - 8.0 (API)

 

[mike007]

Salinity is a little low. You should be at 1.026 but I would think the lighting is the issue. I have never had luck with mushrooms under halide lighting. You might try placing in a darker area of tank with little flow.

 

[MiniDevil]

Thanks I'll give it a shot. Can't hurt much.

 

[Diamond1]

Could be too much light. I run t5s and I have to keep my mushrooms in the lower part of the tank. I've also noticed my mushrooms do better with a little bit of nitrates and phos. With GFO, Carbon and cheato they may not be getting enough nutrients from the water column.

My ricordias seem to do ok under brighter lights but rhodactis and actinodiscus do better in subdued lighting.

 

[SantaMonica]

Also since the nutrients are low, the babies might be growing into it ok, but the parent was used to more nutrients and is now having trouble.