UV for 425XL 25W vs 15W

[RKeenan]

I am trying to get a UV put in as I am down to building manifold for new tank. The problem is the Aqua 25 watt I got will only fit horizontally (along back wall) but with the outlets facing up is a real pain to try and not have hard plumbing with crazy amount of elbows killing flow. Intent on running inline from return pump (Varios 6) straight into return. Could easily do it with outlets facing sideways or down. I know this is a no no but only other viable option I can see is getting a smaller15w and then can mount it horizontally on the sides but they seem to be a good bit undersized for my tank and flow. So which would be the lesser of 2 evils? Outlets out the sides on 25w or smaller 15 unit with outlets up?

 

[lapin]

I dont have that UV but i have mine pointed sideways and do not have any issues with trapped air