suction-side cleaner or pressure-side

[sailork]

The advantages of a suction side;
1. Cheapest by quite a bit. Cheapest to buy. No extra pump. No extra electricity. Fewer parts to break (cheapest to maintain.)
2. When they suck something up it goes to the main filter. If it sucks something tiny off the bottom, you never see it again. The pressure side cleaners scrub a little better, but the debris ends up in a mesh bag. The bag has to be cleaned, and doesn't get the fine stuff.

Disadvantages.
1. Many people have trouble getting them to do a thorough job cleaning the sides, etc. (I use a brush every week or so, it takes me less than fifteen minutes depending on how much beer I drink while I do it.)
2. Your filter has to be cleaned more often.