I'm curious what you mean when you say that they "remove too much".
I use a Pur, tap water filter for my animals, and I still worry about what it DOESN'T filter out.
I don't know anything about the Pur filters but the idea is that some of these filters may be removing trace elements and minerals that the animals need. The Brita, for example, removes calcium (and so I'd never use it at all when snails or stony coral are concerned). I also feel that by removing so much, you're lowering the buffering capability of the water--which could result in more drastic pH swings (which would of course be very stressful to the fish). A steady pH is usually more important than getting the "right" numbers.
Usually the argument for using these filters for aquariums is "they don't remove that much, they use carbon like an aquarium filter". If that's the case, I think it'd be a lot more effective to buy some aquarium-grade activated carbon and stick it in the aquarium filter!
I definitely understand why they're used for humans, dogs, cats, birds, etc. But for aquatic animals, I'm not too convinced. At best, they don't seem to do much at all for aquariums (nothing that can't be accomplished using a $4 bottle of Prime). At worst, they could cause a fluctuating pH (especially since they become less effective as they age and the pH might start rising) or remove something that the animals need (calcium being a definite one).
If you've had good experiences, though, please share. I don't know a lot about using them for aquariums--always seemed risky and a waste of money (for me I guess it is anyways since our tap water is awesome). I don't think I'd ever use a Brita to begin with, though, since the majority of my aquariums are marine and calcium is an important element for marine set-ups.