DE filter definitely clears up your water. I cant decide for you if its worth the expense and I dont think you need one but if you object to me giving you advice then thats okay. (why dont you look up devils advocate?)
I have both the Vortex XL and a System 1. They are both great pieces of Equipment. The System 1 is the easiest to deal with. The Vortex is alittle more involved. But I use that on the bigger tanks when time is really needed. System 1's aren't that expensive now the use the modified model no expansion kiy needed. I use DE filtration once a month just a little thing I prefer to do.