Bali Green Slimer - Tips turning purple

[JSB]

I have a 8" bali green slimer in my tank which is showing growth and polyp extension, but the tips are turning purple over the last week or two. I googled it, and it has happened to others, but no one has an explanation that I can find.

I have a 2" frag of the same piece mounted 4" away, and it does not show the same coloration (yet). My question is whether or not this is bad. I actually like the color. I would post pics but it is already late. I will try to get some up in the morning.

Tank params are
60g cube w/ Radion LED
1.026 SG
temp 80-81 (up recently from 78-79 due to pump change out) could this be the root cause?
po4: 0
NO3: 2ppm
alk 8.0
ph 8.1
ca: 440
running bio pellets and carbon

 

[JSB]

-deleted

 

[ritter6788]

Is it growing?

 

[Frick]

Are you sure it's a slimer (Acropora yongei)? This name gets misidentified on alot of green Acroporas. Got pics? Close ones?

 

[JSB]

These pics are a few days ago, and not the very best. Is it growing? Yes it appears to be growing well, about a 1/3" a month or more on the tips. I fragged a 3/8" diameter limb and it encrusted the cut in about 10 days, so I took that as a good sign.

 

[Frick]

I think you have Acropora pulchra which can get bright blue or purple tips.

 

[JSB]

A. Pulchra may be right, but I guess it is more color change on the ends of the limbs, as opposed to the tips. The color change is reaching down some limbs as much as an inch. Almost browning. I may have just made it angry with the temp change, or the increased flow over the bio pellets and GFO due to the new pumps. After finding my Red Sea test kit was wrong and that I had 0 PO4 as opposed to .8, I removed the GFO, but that was after the heat and the color change.

 

[_Alex_]

Hmm I have a very similar frag that looks just like that and coloring up about the same. No idea on name though as I got it from bigb (Bil brothers) who passed away recently.