Rainbow Bubble Tip Anemone Changing Colors?

[liam’s little reef]

Hello Everyone.

I have noticed that my Rainbow Bubble tip anemone is starting to change colors/pigment. When I first got him (about 2 months ago), he was perfectly healthy and his colors popped. What I have been noticing is that he is turning a brownish purple!
I have an innovative marine fusion 20 gallon that is about 8 months old. For equipment:
Ai Prime HD
Coralife Nano Skimmer
Fluval 20 H.O.B filter(I am using this as a cheap carbon reactor. It actually works quite well as tumbling the carbon)
I dose with Seachem Fusion 1&2

Parameters were checked today using Red Sea and Salifert test kits:
Calcium:420ppm
Magnesium:1400ppm
Alkalinity:9.5dkH
Nitrates:0
Phosphates:0

I really have no clue as to why this is happening to my anemone. He is still eating frozen krill and mysis with a good feeding response, and all other corals in the tank are thriving. I will post before and after photos. The blues wash out the second picture, but you can see the distinct transition of color. Please help!

 

[Reefing Madness]

 

[LesPoissons]

So first off, Nems can change color. Not drastically, (like you wont buy a red and eventually get a green) but they can certainly change. I have a red bta that was a beautiful pink and now it's a ruby rainbow. I had an ultra green bta that got enormous but turned a boring shade of brown. I have a green acid rain that was speckled with blue and white and now the green is much brighter and you only see some blue. Different lighting, different nutrients, different food, flow, water parameters etc can all affect how your nems look. He looks perfectly healthy in the pics, but your tank and lights are not the same as where you purchased him from so a change in coloration is not surprising.

If your tank is only 8 months old sometimes stable parameters are an issue which also affect nems. There are some water parameters you could correct and probably get a better outcome. Your Alk is higher and you may want to consider bringing it closer to 8/ 8.5. Also important: Corals and nems like some phos and nitrate in the tank. Forget about trying to secure 0s, you starve the tank. Get your nitrates to 5ish and phos to 0.1 to start and you will def see better growth and coloration. Do it slowly so as not to generate a huge algae bloom.

Also- side note... carbon shouldnt tumble. In a carbon reactor, the carbon is packed between 2 sponges so it cant move freely. Otherwise the pellets grate against each other and crumble and that abrasive clingy carbon dust is all in your tank. If your carbon is freely tumbling... you may want to stop that.
Hope this helps!