Above Ground vs below ground products

[jesse]

So I just bought a house with a below ground pool and an doing reasearch. I noticed that above ground products (pums, auto cleaners, chlorine generators, etc) cost much less than below ground. Why? I realize that pumps have to be self priming, but what's the difference for chlorine generators (since that's what I'm really interested in).

[Poolz]

The differences reflect the size, quantity or capacity of the equipment in question.