It looks like the entire filter is sitting up off of the tank, instead of it sitting all the way over and down.
If that's the case then the filters are to small for the tank or the tanks edge is to thick for that size filter.
If it is up above the edge it won't ever not splash because it's to far away from the surface.
Some of the older tanks have really thick rims and a lot of regular filters won't hang right. I know this because I happen to have bought one through craigslist several years ago.
The only way I found to get a filter to work was to use a HOB
Canister with an adjustable hanger. This one works really well, it's for up to 55g tanks. The outflow can also be set so that there is 0 splash, or just a small amount for air.
Sorry about the crummy pics. it's 1:30am and the room is really dark.
Anyway in the second and third photo's you can see the the hanger moves in and out to accommodate any size rim, from a rimless tank to a tank with a 4" thick rim. I use 2 of them on my 55g Mbuna Tank and they keep everything crystal clear. I only have to clean them every 6 months. It is an extremely low maintenance filter. The one in the pic. is 7 years old, I replaced the gaskets once about three years ago.
Right now you can get one for $51.99 at bigalsonline. It's a great filter for the money.