Overflow or Normal?

I purchased an Eheim 2250 from someone and he had it setup with an overflow box. I currently have it running but it's quite a pain to maintain. When the water level gets low and the overflow drains, it's a big air bubble in the 2250 and the filter stops. I have to empty out the canister again, grab the bucket and fill more water until there's more than enough then get the overflow going.

The big plus with the overflow is it keeps the surface really clean and free of any debris and film. This I really like.

Should I keep the overflow or should I put back the original intake tube that goes inside the tank? Any advice would be greatly appreciated.

I might just go back to a regular intake but I'll see how the overflow goes. I think I'll just have to keep an eye on it and keep topping it off. I've never had one before and this is my first big tank. I was quite surprised at how quickly the water evaporates. Thanks for the suggestions. I'll check out skimmers the next time I'm at BA's.