Papa
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Lost,
i think i see what you're asking . . . and after rereading ben's post i think i see the problem.
ben wrote: "Here is a list of water temperatures and the amounts of dissolved oxygen that water contains in relation to these temperatures:"
as i understand it, it should have read "Here is a list of water temperatures and the saturation level of dissolved oxygen that water may be able to achieve:"
as i understand it, there is a maximum level of dissolved oxygen (DO) in water that can be achieved. this maximum level is referred to as the "Saturation Level." the saturation level can vary because of at least three factors: temperature, TDS, and atmospheric pressure.
by cooling our reservoirs, we are trying to increase the capacity of our water to hold more DO.
let's take your example: a reservoir of 74°F nuted water with DO of 6.3 ppm. perhaps it's stagnant, maybe it was aerated a while ago, maybe not, we don't know. what we do know is that it's 74°F and has a DO of 6.3 ppm.
ben's post tells us that 74°F water (likely 0 TDS and at sea level) is capable (in ideal lab conditions) of achieving a maximum of 8.5 ppm of DO.
your 74°F nuted water at a DO of 6.3 ppm isn't yet saturated. (maybe it is, depending on how much stuff you've added to it, maybe not).
let's stick a venturi in that bucket and see if we can get those DO numbers up!
yep, that's great, we've aerated the bucket with a venturi and the DO has risen to 7.6 ppm! that's about 20%!
what ben's post tells us is that no matter how long we keep that venturi going, and no matter how pure we make the water . . . we ain't never getting the DO higher than 8.5 . . . unless we drop the temperature. if we drop the temperature from 74°F to 65°F >>>> we may be able to achieve an additional 10% increase in DO!!
i hope this helps.
Papa
i think i see what you're asking . . . and after rereading ben's post i think i see the problem.
ben wrote: "Here is a list of water temperatures and the amounts of dissolved oxygen that water contains in relation to these temperatures:"
as i understand it, it should have read "Here is a list of water temperatures and the saturation level of dissolved oxygen that water may be able to achieve:"
as i understand it, there is a maximum level of dissolved oxygen (DO) in water that can be achieved. this maximum level is referred to as the "Saturation Level." the saturation level can vary because of at least three factors: temperature, TDS, and atmospheric pressure.
by cooling our reservoirs, we are trying to increase the capacity of our water to hold more DO.
let's take your example: a reservoir of 74°F nuted water with DO of 6.3 ppm. perhaps it's stagnant, maybe it was aerated a while ago, maybe not, we don't know. what we do know is that it's 74°F and has a DO of 6.3 ppm.
ben's post tells us that 74°F water (likely 0 TDS and at sea level) is capable (in ideal lab conditions) of achieving a maximum of 8.5 ppm of DO.
your 74°F nuted water at a DO of 6.3 ppm isn't yet saturated. (maybe it is, depending on how much stuff you've added to it, maybe not).
let's stick a venturi in that bucket and see if we can get those DO numbers up!
yep, that's great, we've aerated the bucket with a venturi and the DO has risen to 7.6 ppm! that's about 20%!
what ben's post tells us is that no matter how long we keep that venturi going, and no matter how pure we make the water . . . we ain't never getting the DO higher than 8.5 . . . unless we drop the temperature. if we drop the temperature from 74°F to 65°F >>>> we may be able to achieve an additional 10% increase in DO!!
i hope this helps.
Papa
