whats a good canister filter for my 45g reef

[asylumdown]

+1 on canister filters being more trouble than they're worth in a reef tank. To keep it properly maintained you'd need to be thoroughly cleaning the sponges/pre-filters in your canister filter each time you did a water change, and i have yet to see a canister filter on the market where that process is easy enough that you'd be happy to do it weekly on a long term basis.

In my first reef I ran a fluval fX5 in addition to my sump, but more because I had one from my old freshwater tank than because I needed it. Draining, cleaning and re-assembling that sucker was awful.

Even smaller canister filters are giant pain, since they're almost never placed where they're easy or convenient to get to, almost always make a giant mess when you open them, and are heavy and cumbersome to move when they're filled with water. They can turn a single water change in to a 1-2 hour affair.

Also, calling them a filter can be sort of misleading. If by filter you mean manually removing solid material and converting it efficiently in to nitrate, then, yes, that's exactly what they do. If you're having algae problems, it's usually (but not always) because you've got too much of the end product of the nitrogen cycle floating around in your tank. Canister filters are designed almost entirely to facilitate the nitrogen cycle, so by their very nature they run a serious risk of making algae problems worse. In a normal reef tank, uneaten food and fish poo gets eaten before it can break down in to ammonia by the scavengers you both paid for, and hitchhiked in on your rocks. And their waste in turn gets eaten by something smaller. But at each step of the process, a certain amount of the nitrogen and other nutrients gets locked up in the biomass of whatever just ate it. The end result will always be ammonia and other nitrogenous waste, but if it works it's way down the conveyor belt of scavenging animals beforehand, the amount of ammonia that becomes available to the nitrogen cycle will be greatly reduced. Canister filters skip all of that by just sucking up the uneaten food and fish poo, where it gets trapped in the filter material, rots, and immediately breaks down in to nitrogenous waste.