Because at the end of the diving day a set of doubles is too heavy to pick up and dunk head first in my washing binSpectre:I never trust those. capping it keeps any water that got in while diving in there; which there shouldn't be; by design. So why makeshift a method to keep water out when you can just use the method designed for it, like Mo2vation stated, and leave it on the tank to rinse?
No probs at the start of a diving day, just no energy left at the end...
Seriously I just put my thumb over the din and give them a good swish around then hang them up.