Filter for 4ft/110l tank

Hi

I'm going to be setting up a 4ft/100l tank soon for my axolotl (looking into getting a 2nd soon). I was wondering if anyone had any advice on what filter to get. I was looking at a Fluval U3 but was thinking that parts of the tank would become stagnant? any advice?

Also could I have an air curtain in the tank to help circulation since it will be a 4ft?

I have a fluval u2 in my tropical fish tank and it's a really bad filter. If you move it all, the debris inside it falls out into the water. It also stops working if I unplug it, I literally have to hit the thing to get it started again. I hate doing water changes and cleaning it out, it makes me not want to. I leave it on now if I'm doing a water change, which you're not meant to do. But if I don't I'll be stood there another 30 mins trying to get it started again. I've read other reviews which say they have the same problem. But then again, there are mixed reviews as other people say theirs works fine.

I had an interpet filter before that in the tropical fish tank. That broke down after about 3 months, but I have one in my axolotl tank which is still going strong after nearly 6 months. - I'll probably get home tonight and it will be broken now
I have the interpet at one side of the tank and a small sponge filter at the other side which really helped my cycle and also adds oxygen to the water.

Try a site called All Ponds Solutions, they have several filters at very reasonable prices. I have 2 filters in my 4ft tank, one on each side, I bought a thje ones with the built in spray bar and it cost me just over £20 for both of them including the postage. In my 3ft tanks I have fluval filters and find the cheaper ones are just as effective.