UV placement

Hi all. I am currently looking to install a uv light on my tank. I was thinking of hooking it up to my co2 reactor return. I have it fed by a large pump and the only thing on it is the reactor.
My question is in regards to whether this is an exceptable place for it. Is there any negative to doing this (co2 protecting any spores or pathogens, uv breaking down co2?
Oh, before anyone wonders why I am putting it on, I am having serious issues with GSA and every time I scrub it off the glass it stays in the water for quite some time and then seems to REALLY attack my Anubias. I raised my phosphates as per other threads but am still fighting it. My phosphates were ~1.5 and now are ~3.5. So i figured we will see if this helps. I had it just laying around from when I got the tank.

Thanks.