I still have my old aquaclear 110 in my basement. i used to use it for my 40 gal. it creates a lot of good flow. there are only two settings on that filter, which are max power and lightly less flow. if you want reduced flow, put a sponge on the intake part. you can cut out the sponge yourself, then cut a hole in it to shove the intake in. this will slow the flow a little more.
That said it should be good for a 50 gal. as long as its not going to be planted, or youre going to have plants flying all over the place lol. thats the reason i changed mine out for a more peaceful canister.