Favia and Mushroom questions

[SMB]

I have an AIO JBJ 45 cube that has been running for 2 1/2 years and very stable.
Water parameters: pH 8.0-8.2, SpG 1026, dKh 9.5-10, Ca 450, Mg 1350, po4 0.2-0.15, Nitrates 4
WC~15 gal. weekly. There have been no recent additions or changes in the tank.
All the corals except the Zoas are over two years old. I do not specifically feed the corals but do use Red Sea Coral Nutrition/Reef Energy additives.

One Favia has lost it's green color in several of the "faces" over the last week or so. There is no tissue loss and the polyps open fully at night. (It started as a single polyp and is now lemon size.)
Any suggestions on the reason for this?

The second question is regarding a Frilly Green Mushroom. Started with one and now have three but it never split. The other two just sprang up nearby.
In the morning before they are fully open, I can see a tear in the original Mushroom. It now has apparently two feet. Curiously on side of the tear does not have an oral disc. I guess it is just dividing but I have never seen that happen before so looking for guidance. (I have nothing in this tank, that I know of that would eat/attack a Mushroom.)
Sorry for the images, I took them without cleaning the glass, changing the light etc etc.
You can see the Favia mid right on the bottom of the tank and the ?dividing Frilly above it on the rock (furthest left of the three.)
Thanks.

 

[Tahoe61]

That sounds like typical Corallimorphia reproduction, lateral fission, and when they move around they can leave just a tiny piece of tissue that grows in to a full mushroom.

What is the lighting type?

Have you double checked or calibrated the instrument you using to measure SG?

Nice tank, Pocillopora sure love it.

 

[SMB]

Light is from a single Kessil 360W on their controller.
I use a refractometer and calibrate with a standard solution ~ once every two months. I'm pretty careful about matching the tank and WC water.

The Pocillopora started as a golf ball sized frag., the bottom piece. It then just stared four other nubs (one in the back you can't see) that have grown as independent pieces.

 

[Tahoe61]

Well I am stumped. It's my experience that the more common reason corals change coloration when phos is too elevated or too low or changes in lighting. Perhaps this is new growth and the area has yet to develop the same zooxanthellae population as the rest of the coral. I would certainly keep taking images for comparison. Are you using any charcoal or phos products or recently changed them out and over polished the water too quickly.

 

[SMB]

Well I am stumped. It's my experience that the more common reason corals change coloration when phos is too elevated or too low or changes in lighting. Perhaps this is new growth and the area has yet to develop the same zooxanthellae population as the rest of the coral. I would certainly keep taking images for comparison. Are you using any charcoal or phos products or recently changed them out and over polished the water too quickly.

Thanks for your thoughts. I just use charcoal (BRS) and try to change it about every six weeks. I have two bags, one in each overflow chamber and try to stagger the changing, dont do both at once. My time table for that isn't that great! but it wasn't done recently.
I have never been able to achieve super low PO4. 0.1 to 0.3 is my norm. Never had any algae even from the beginning. Clean the glass with the WC once a week but it barely needs it. I use RO DI water and have tested it, 0 TDS and PO4.

The Favia doesn't seem to be getting worse but if it doesn't change for the better I will send of a Triton test kit.