Welcome to R2R! I think a 40 gallon is an excellent choice for a first sw tank. Canisters can work fine but can be a bit harder to maintain in the long run. A sw tank doesn't really need as much filtration as a fw tank as long as you have a good bio filter (rock) in the tank. I've run tanks with canisters, HOBs and corner filters as well as all-in-ones and sumps, even undergravel. They can all work but I think the canister was the hardest to maintain. Kind of out-of-sight-out-of-mind thinking on my part
I've browsed this forum a lot and decided to start up a saltwater tank even though I won't be able to get the lionfish I have always wanted over here. I have been working with freshwater and brackish for years but I thought it might be fun to try coral instead or plants. I'm looking forward to the experience. I am considering using a 40-gallon tank to start. Do guys think that's a good beginner's size? I'll either put in overflow or use a canister filter but I've read mixed things about using canister filters
You can always try drilling the tank for an overflow. It seems intimidating but they make them with kids and I've never had any trouble. I've also been looking into the mame hang on back overflow which can supposedly restart siphon
