What canister filter to use?

[paddyob]

I used a hot magnum in my 20 for 4 years. My tank was great. No issues what so ever related to it's use. It was a pain to maintain a HOB canister so I removed it.

I ran carbon and foam only. Which was changed monthly.

I am now adding a Rena xp1 to replace my not-so-reliable-during-blackouts aqua clear.

If you clean it monthly, you will be fine.

Avoid fluval entirely. A nightmare to service. And it needs priming manually. Junk.

Rena is self priming and easy to maintain.

[goby1]

Thought I would attach a photo of my tank as the tank you are describing is pretty much this one - 46g with hang on Remora skimmer with the in-tank skimmer box. I used to run a Rena cannister but it started to leak and by the time the replacement part was in I had scrapped it - total PITA to clean. I have 50 lbs of live rock with various softies that are easy to maintain (I don't have a lot of light - 96w 50/50 PC) and I do a 25% water change every two weeks. I don't have a glass top and the lights are on legs, not hanging above. I think if you can swing a sump it is easier and takes all the equipment out of your tank. But if you don't this is pretty much what it's going to look like and I think you need to keep it FOWLR with softies IMO. Trying to run a full reef with the lighting that is required is going to be more trouble than it's worth IMO.