GSP spreading rapidly but not opening fully

[the_bandit]

I have had a medium colony of GSP for well over a year now that have spread a lot. Ever since I changed my lighting from a PC 4 bulb system to a 250w MH, they refuse to open all the way. The MH has been up and running for at least 6 months now. The GSP colony is on the lower 1/3 of the tank and gets moderate flow. I have moved them around and positioned them differently but nothing seems to work. The odd thing is when the lights are off at night and in the morning when there is ambient light, they open all the way. All other corals are opening fully and thriving.
Any suggestions?

 

[geoj]

How long is the MH on?
Did you give them a chance to sit in one spot for 2-3 weeks?
You could try more flow; they tend to open more in good flow
I have some GSP frag remnants under a 250 MH 15k on 6 hours a day. I have neglected them but some of it opens all the way other are being stung by some Rics, but I can’t rule out the high light. I would think they would do fine under 250 MH.

 

[the_bandit]

The MH is on for about 7 hours. I have two different types of GSP if that is possible. Normal looking GSP and then smaller, thinner GSP. Its kind of hard to explain but the smaller type fully open. The ones that dont open get nice random flow so I ruled out a flow issue. I just dont understand why they are spreading at a fast rate but not fully opening.

 

[flower]

Try placing the coral on a steep angle…on its side. That way it gets indirect light which from the info you gave, that’s what it prefers. You can also try placing it in the lower part of the tank near the bottom.

 

[mattzhawk]

Mine are under a 760watt mh-pc fixture, mine open up but I have some button polyps that tend to close up a little when I turn my mh's on but open fully when just running the pc's. What is your water temp with the new fixture?

 

[the_bandit]

the tank runs around 76-78 on a daily basis.

 

[jstdv8]

I beat my GSP like a rented mule with flow. looks like a green field of grass in the summer.
I don't have MH's though