Just curious as to what effect useage in chlorinated pools would have on uw housings in general? If at all?

If housings are heavily used in chlorinated water then their 'O' rings should be replaced more frequently than if they are used in salt or freshwater. A good recommendation is to halve service intervals. What I have personally seen happen is heavy, prolonged and extensive use in chlorinated water leading to the removal of grease from areas of heavily used control 'O' rings (the shutter release for example) simply through use, and probably some interaction between the grease and chlorine, which then allows the 'O' ring to deteriorate due to the chlorine. This will cause it to bind and the control to stiffen and if not dealt with the 'O' ring will then fail. If such a control is stripped down the 'O' ring leaves a liquiidy black residue (at least in the case I dealt with this residue was between the first and second 'O' ring) which seems to be the result of chlorine and nitrile rubber reacting. I hasten to add that this requires a very great deal of use of the housing in chlorinated water, but I would always suggest that any housing used a lot in chlorinated water should have double 'O' rings on its control shafts.

Tap water (at least in the US) can contain as much or more chlorine than a properly chlorinated pool.

US EPA standard for max chlorine: 4ppm
Typical pool standard: 1 - 3 ppm

It's actually a bit more complicated than that... there is chlorine, chloramines, and chlorine dioxide, and a ton of different delivery chemicals... Certainly people do over-chlorinate their pools, but I'm wondering if some of the effects Paul mentions are more related to pH. And some of the other water conditioning chemicals. Oh, and pee.

Cheers,
Cp

Having discussed this with an 'O' ring technician(!) I'm pretty sure that the free chlorine is the culprit when it comes to the actual damage to the nitrile rubber of the 'O' rings - I don't know if silicon 'O' rings suffere though.