The Puffer Forum

Flutter wrote:Gross, I hate beer head.

You mean the state of mind or the actual part of the beverage?

The actual part of the beverage. It's foamy and nasty and *shudders*.

Nick: Your post confuses me. Nitrogen (78% of the air) is about twice as soluble as oxygen,(21% of air), while CO2 (way less than 1%), regardless of molecule atomic weight, is far more soluble than either. Carbonated water has nothing to do with normal off-gassing of dissolved air under pressure. Normally O2 should come out first, but N2 is there in almost 4x the concentration, and the fact that it is ~2x as soluble has little impact. Once a microbubble forms, whether O2 or N2, supersturated N2 is going to come in much greater absolute quantity than the other, trace, gases and than even O2. The bubbles will be largely N2 until a lot of it is out of the water. Off-gassing is not at all slow. An hour loses almost all of it. CO2 may be a tad above normal solution level, as may O2 . But with circulation sufficient to ripple the surface even w/o splashing, it should be only trivially different from static solution of dissolved air gases.

The only reason it takes longer for a glass of cool tap water to show bubbles with standing is because that case requires separate warm-up time to room temp. Pre-mixed water for changes is drawn at tank temp (82-84F for Discus) so it is already warm. Any agitation in effect forces the gases out. Tanks do not lack fine particulates and other points for nucleation. The incoming water is relatively fine particle free.

Dissolved gases don't "settle", they volatilize from dissolved gas to just gas. Particulates settle. Dissolved things don't. Have I ever warned you that I am a nit-picker? When you go into lab-speak, terminology gets tighter.

Yes, I got confused rereading it too now that I go back; I wish I could set up a filter on this board in order to make me sleep and reread my writing before posting when I miss a night. Stream of consciousness rambles and chooses words poorly, or switches them.

That is a relief - I thought it might be be my poor vision...

Nope, definately me, I'd edit it, but now it's almost funny to me.

RTR wrote:I used to be a diver myself, so I had heard all the horror stories about the bends

Robert, I missed that sentence! I had no idea... Been diving for 12 years. Hubby has experienced being bent 2x.

Pufferpunk wrote:

RTR wrote:I used to be a diver myself, so I had heard all the horror stories about the bends

Robert, I missed that sentence! I had no idea... Been diving for 12 years. Hubby has experienced being bent 2x.

I'm a diver and had 2 x hear operations last year to close a pfo (hole in heart) after having the bends 2 x confirmed and 1 x suspected. They're not fun but I was lucky and only had minor bends so could still function.

I never thought that fish could get them, or their equivalent though. I'm not scientifically minded (takes me ages to learn new dive theory) so could someone please explain very simply regarding this and fish?

Thanks!

Simplest terms I can manage: Cold water holds more dissolved gases, lots more, than the same volume of water at higher temperature. Plus, pressurized water holds more dissolved gases than water at ambient pressure, again, lots more. Draw cold water from a pressurized line, adding hot water at the same time to bring it to tank temps. Bingo! Gases start coming out of solution - fast. This includes in the gills of the fish, and in the capillaries of those gills. microbubbles join together to build macro-bubbles and more gases join those bubbles - making them grow. Almost 4/5 of air is nitrogen - the bubbles are also mostly nitrogen. You can get embolism blocking small arteries and veins, you can get smaller bubbles blocking critical veins, Effectively you can have any or all of embolisms and/or strokes and.or coronaries - any or all together, and any one can take you out. Divers have some of both worlds - they are breathing compressed air at normal depths and have high levels of dissolved nitrogen and the other lesser gases in their blood. Slow ascent with pauses at certain levels for slow breathing helps clear those gases quite well. Too fast an ascent and you surface with too much nitrogen in the blood, and it starts building bubbles in you blood. Micro-embolisms in muscle tissue hurt like - well you already know. The same in coronary arteries are effectively small heart attacks, and may also hurt the same or worse. In the brain, they may or may not hurt. Large embolisms in the lungs (humans, not fish) tend to be painless or relatively so, and can take you out fast, but they ar or were considered uncommon in divers who did not decompress well enough.

Does that make sense and help?

PP - I had stopped SCUBA long before I met you. My wife did not even know how to swim! When our son was born, I insisted that he learn to swim very young, so he went to AU for infant lessons/training. Herself took off work during his early years, so did the training session runs. She was embarrassed that she could not swim at all, so took lesson in parallel with the kid, but never went far enough or got enough confidence to dive. She would do snorkeling with me and later us all together, but I let my dive certifications lapse and never went back.

Cold water holds more dissolved gases, lots more, than the same volume of water at higher temperature.

Soooo... my comment is: In the winter, the water coming out of my tap is way colder than in the summer. Yet I still fill the tank with 84 degree water, winter or summer. I just use less of the colder water in the mix. Much less. When I turn the spigots in the summer, the cold is open all the way & the hot, just a little. Opposite for the winter--the hot is open all the way & the cold just a little.

Yup,fairly standard for fresh drawn water. But there is a bit of a lag behind the seasons - summer heat lingers into fall, and winter cold is just now peaking, even though our snow is finally melting.

My water heater is set hotter than most folks. I never have to open it fully. Plus, it lives in the tank room and the pipes are insulated all the way to the immediately adjacent sink... and the whirlpool tub in the adjacent bathroom. The whirlpool's pump and heater are in the corner between the sink and the hot water tank.

But the difference in gas solubility in cold water out-weighs the reduction in the volume required.

Thanks, that's what I was wondering. Tomorrow's WC day again. Gonna do 2 x 50% WC, a few hours apart.

You should be fine.