Question for kessil pros regarding acrylic cross bars

[acropora4u]

I have a cross bar on top of tank pictured below and was going to hang a kessil a500 above it as that’s where it fits in my set up. Will i loose and a lot of par because of the acrylic bar?

 

[Reefer Matt]

As long as it is kept clean you shouldn't lose much, if at all. I use polycarbonate (clear) covers on my sps tank and have par mapped it with, and without covers.