Fish are getting sucked into the skimmer

[tadpole]

Originally Posted by rlitman

Also, while cold water does retain more oxygen, and the fish's metabolism is extremely slow in the cold, the actual volume of dissolved oxygen is still staggeringly low, and can be used up.

What do you base this on?

[rlitman]

Originally Posted by tadpole

What do you base this on?

http://www.engineeringtoolbox.com/ox...ter-d_841.html

Note that the units are in milligrams per liter, and that the chart is assuming pure oxygen. Atmospheric pressure is 1 bar (at sea level), but the oxygen partial pressure is just 1/5 of that, so the solubility is 1/5th the number at 1 bar.

Assuming you have a 1000 gallon freshwater pond (salt reduces the solubility), at 32F, you could have as much as 0.27 cubic feet of dissolved oxygen. At 68F that number drops to a whopping 0.17 cubic feet dissolved in that entire 1000 gallons.

[tadpole]

Originally Posted by rlitman

http://www.engineeringtoolbox.com/ox...ter-d_841.html

Note that the units are in milligrams per liter, and that the chart is assuming pure oxygen. Atmospheric pressure is 1 bar (at sea level), but the oxygen partial pressure is just 1/5 of that, so the solubility is 1/5th the number at 1 bar.

Assuming you have a 1000 gallon freshwater pond (salt reduces the solubility), at 32F, you could have as much as 0.27 cubic feet of dissolved oxygen. At 68F that number drops to a whopping 0.17 cubic feet dissolved in that entire 1000 gallons.

Correct. Warm water will hold less Oxygen than cold water. That is not what you implied in your post.

http://www.insiteig.com/pdfs/solubil...n-in-water.pdf

There is more Oxygen, by volume, in cold water (when the fish don't need it) than there is in warm water (when the fish DO need it). One of nature's conundrums.

[rlitman]

Originally Posted by tadpole

Correct. Warm water will hold less Oxygen than cold water. That is not what you implied in your post.

Sorry, I take that as a given. Yes, warm water holds less oxygen, just when fish need it most.

I'm just saying that even in cold water, the maximum amount of dissolved oxygen is very small. Oxygen's solubility in water just isn't that great, and no matter how slow a fish's metabolism is in cold water, the amount of available oxygen is still finite.