What is going on with my torch?

[Randomstylez]

I have had this torch for 3 months. The first 2 months no issues. It seemed to be growing fine and was happy. Over this past month the torch has slowly retreated inside itself. I thought I would let it ride out as time went on and see what happens before I step in. The torch continued to retreat back into its self until I could no longer see any polyps. I don’t know if I should step in now if there is a problem or not. It has only been 2-3 days since it has gone all the way in.

background information

my tank is 7 months old, 13.5G and I have been battling and beating chrysophytes. My parameters rarely change, but to coincide with the timing I started adding phosphate and nitrate to stop being at 0.00 phos and nitrate to beat the chrysophytes. I also added a small power head so as to not let them settle on the rocks

my current parameters are
Ph 8.2
Alk 9.5
Calcium 470-500
Magnesium 1480-1540
Nitrate 2- 4
Phosphate 0.01-0.02

Everything else in my tank is growing quickly

 

[MyOtherCarIsAFishtank]

It's hard to say. Torch corals can be very finicky. Do you have any fish, inverts, etc. in the tank? Is it right in the line of your flow?