What size t5 retro?

[SpikesReef]

I'm going to install a T5 retrofit kit inside my hanging canopy with LEDs. This is going to be on a 40b (36").

Would I want to use the 2ft or 3ft retrofit kit? I would prefer 2ft but not sure if that will cause shadows on the sides of the tank.

 

[CodyRVA]

I would go with the 3 foot light to match the tank width. I have a 4 foot system with an ATI 4 foot fixture and IMO you don't want to go short. Ultimately it depends on what you want in the tank; sps: go full width, softies or fish only: probably could go with the undersized fixture. How many bulbs?

 

[SpikesReef]

Only two. One in front and one in back, mainly to add more actinic and reduce shadowing from the LEDs

 

[CodyRVA]

Only two. One in front and one in back, mainly to add more actinic and reduce shadowing from the LEDs

Gotcha. In all reality, if its purely supplemental then you could go shorter. Depends on your LED's and what you're after as far as coverage. If you already have the ends covered with the LEDs then shorter might be better. Save some $$$.