Water ingress to BCD

[Foxfish]

After diving salt water I deliberately use a hose to put some water in the BCD through the dumb valve.

So that would be water egress through dumb valves while diving in the poo.

 

[Doc Harry]

I noticed when getting out of the poo...

It's been so cold around here that I've been pooing in my dry suit just to stay warm.

Back to the topic....

I find that if my weight is correct I will have water in my BCD at the end of the dive. Let me explain.

If your BCD contains air and you depress the valve to dump, then air will be forced out of the BCD by the water pressure exerted on the outside of the bladder of the BCD.

Now if you are weighted properly, then at the end of your dive your BCD should be empty and your buoyancy is controlled with your lungs. Should you depress the dump valve at this time, you are doing nothing more than allowing water to enter into your BCD.

If you are diving in salt water, it would be a good idea to rinse out the inside of your BCD after your dive, and to thoroughly rinse the inside at the completion of your dive trip, in order to preserve the plastic liner.

If you are diving in fresh water, then it would be a good idea to chemically sterilize the inside of your BCD after your dive to prevent cross-contamination of bodies of fresh water, especially if there are algae issues in your area.

EDIT: Water in your BCD does not affect your buoyancy. That is because water is essentially incompressible, so water in the BCD neither makes you less nor more buoyant.

 

[CT-Rich]

I usually rinse the BCD by loading water in through the Inflator with a garden hose slosh it around and inflating it and letting the air pressure and gravity force it out. I used to add some vodka to the bladder for winter storage, but have since decided that was a waste of good vodka...

You will always get some water... it is just a question of degrees (unless you are using your drysuit to control buoyancy). On the surface you will dump air to descend and at depth you will add air for trim and dumping it as you ascend. Unless you are incredibly lucky each time you open the valve, depending on your orientation, there is an opportunity for water to get in the bladder. I like the suggestion of sterilizing the inside of the bladder when going between bodies of freshwater.