All the different types of filters have their plus and minus. Really what it comes down to, is your preference for maintenance.
Sand requires backwashing periodically and probably a deep cleaning every couple or 3 years.
Cartridge filters do not require backwashing, but you have to take the filters out and hose them down when they get too dirty. Another downside is if you get algae, you may have to clean filters several times a day. The filter stuff REALLY well. Another downside, is you will have to eventually replace the cartridges after some years. You can expect a set to range from 200 to 300, depending on how large the cartridges are.
DE Filters also filter REALLY well and so may need backwashing and DE replacement often, as well as grid cleaning.
The larger the DE Filter you have, the better as you get a longer period of time between cleaning
I have Cartridge and I like it really well. As for size, when it comes to cartridge filters, get the biggest one you can afford. The bigger they are, the less often you will have to clean them. FOr your size pool, I would recommend at a very minimum, 320 sq ft,If you can afford bigger, then you will be glad you did.
I have a ec75a Hayward pump and filter setup. This Hayward is junk from my experience so far. From what I can tell cartridge filters seem to be the way to go for any new pools. Can you guys tell me why I should or should not do this, and if I should, which filter should I get for a 25,000gal pool?
Thanks for your time.