I think you miss understand how UVs are sized. That is the right size UV if you want 30K, but if you are looking to use it for anything other than basic clearing of water you will need to run it at more than 30K. For example if you want to help control disease and paracites you need to run near 90K-180K. It's the size they recommend for your tank based on running it only at 30K. But if you just want clear water than 30K will due just fine.Going larger on the UV is always an option, but I felt it better to start with size that lifeguard recommends for my size tank. At this point I don't see the need to run a UV rated for nearly 3x my tank size. My UV will be ran off of a manifold, so if I need to upgrade in the future it will be easy to do. I would add an algae scrubber before upping the UV size if I find it to small to keep up with my tank however.