Camera time underwater

how long should i spend underwater with a WP-DC 16 case?

At least five minutes less than the amount of air you have left.

I often ask dive guides who have these plastic compact housings - how long they last being dived every day. It is a bit of a how long is a piece of string question - but after about 300-500 dives they tend to get "unreliable".

Alex

^ I guess that's reasonable considering how cheap they are