HQI distance from Acrylic tank?

[cmack]

I'm building my canopy for my 180g acrylic, it will have 3 - 250W HQI fixtures, and 2 - 72" VHO actinics. How far from the Acrylic tank top do I need to have the HQI fixtures? I don't want to melt or warp anything, but also don't want to sacrifice too much of the HQI power.
Thanks

 

[kpatrick]

not sure about acrylic but I keep my 250 HQI about 5" away from the glass support beam along the top of my tank and havent had any heat issues. I also have plastic lunar lights about 5 " next to them and it doesnt melt the plastic lunar lights.

 

[cmack]

anyone else??

 

[johnic]

I just purchased (2) 70W HQI's and I also have an Acrylic tank. I removed the 2 removable covers at the top and mounted the fixtures directly over the water to also allow heat to release and not melt covers.