Gussie,
As KimKats mentioned above there are LOTs of discussions about the different types of filters on this site. You can find them by searching. There are also some very strong beliefs that each one is best. So this sort of depends on who you ask. I'll try to summarize in an unbiased way:
- There are 3 types sand, DE, cartridge
- All three work and are used in pools successfully
- Sand is the oldest and so it's probably the most common
- DE and Sand consume more energy because of the complicated piping but the increased amount of energy consumed is probably not that significant to your electric bill
- DE and Sand require back flushing that consumes a lot of water. If you are in the lower tier of your water bill costs or water is cheap in your area this probably isn't a big deal unless you care a lot about environmental issues
- DE and cartridges can remove particles down to a couple of microns and generally DE is accepted as the best. This is way better than sand performance which traps particles down to 20-40 microns. But the truth is that pools don't need better than 20-40 micron filtration to look great.
- DE and sand need require more maintenance (mostly back-flushing) than a properly sized cartridge.
- DE is most expensive, sand is next and cartridge filters are cheapest. The cost difference can be significant.
- DE is outlawed in some municipalities because it can cause plugging and other damage to sewerage treatment plants.
[*]All need to have their media replaced over time.
- There have been big advances in DE and cartridge filters in recent years that address the DE loss issue and paper filters are now made of polymers that last a long time (3 seasons or more).
- Cartridges need to be cleaned by removing and spraying off. This is a little more work than back-washing but takes only 20 minutes or so and is only needed once or twice per season for properly sized units. Cartridge cleaning uses way less water than back-washing.
There you have it. The pro's and con's as unbiased as I can get. You can find experts that will tell you each one is best. When that happens I take it to mean they all work well enough. All you need to do is make the choice that's best for you.
I hope this helps.
Chris