Need some help please

PDS

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Aug 28, 2007
20
Northern Kentucky
Hi all,
I have an AGP and noone has swam in it since Sept 3rd but the water level has gone down about 3-4 inches. It's a brand new pool, Do you think I have a leak or is this pretty normal? Thanks in advance for any help/comments on this.
 

duraleigh

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Apr 1, 2007
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HI, PDS,

Welcome to the forum. Water levels in the South typically drop 1/4 inch (give or take) per day from evaporation and whatnot. If you haven't added since Sept 3rd (17 days), that's about 3-4" so I would suspect it's normal. No guarantee that you don't have a leak, but that seems pretty typical of pools here in the South.
 

donaldm823

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May 21, 2007
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Cape Coral, FL
Evaporation Loss at Night

I have seen the majority of my evaporation occur at night if the night is cool and the pool water warm. Here in PA it typically goes down to 60F at night with my pool water at 85F-you can see the steaming off of the water surface-which is water loss. I control it now by installing my solar cover at night-it minimizes both the heat loss and the fluid loss. Not sure if you are in the Kentucky mountains, if so you may be seeing the same thing as I.
 

duraleigh

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Evaporative loss is normally greatest when the temperature/dewpoint spread is the widest.....mid-afternoon on a normal, clear day. Wind (mixing of the atmosphere) is a significant contributor.

The "steam" you see (usually at night and early AM) is actually condensation. The air temp just slightly above the pool water warms a little and is able to accept more water vapor (gaseous). As that tiny layer of warmer air rises, it is quickly cooled by the surrounding atmosphere and becomes totally saturated....producing condensation (wherein the water vapor returns to it's liquid state).

You do not see the "steam" (condensation) in the daytime because the surrounding atmosphere has a wider temp/dewpoint spread and can accept far more water in it's gaseous state. The greater the temp/dewpoint spread, the more evaporative loss occurs. Those of you living in the desert Soutwest in that low relative humidity can attest to that.
 

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donaldm823

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May 21, 2007
148
Cape Coral, FL
duraleigh said:
Evaporative loss is normally greatest when the temperature/dewpoint spread is the widest.....mid-afternoon on a normal, clear day. Wind (mixing of the atmosphere) is a significant contributor.

The "steam" you see (usually at night and early AM) is actually condensation. The air temp just slightly above the pool water warms a little and is able to accept more water vapor (gaseous). As that tiny layer of warmer air rises, it is quickly cooled by the surrounding atmosphere and becomes totally saturated....producing condensation (wherein the water vapor returns to it's liquid state).

You do not see the "steam" (condensation) in the daytime because the surrounding atmosphere has a wider temp/dewpoint spread and can accept far more water in it's gaseous state. The greater the temp/dewpoint spread, the more evaporative loss occurs. Those of you living in the desert Soutwest in that low relative humidity can attest to that.
Your explanation sounds real "official/technical" to me, but condensation means my pool level should rise-which in fact it does not-just the opposite. But my solar cover comes off every day at 1200 and back on at 1800. The only time my water level goes down is when I do not install my solar cover at night. I also run my pool pump ONLY during the day. With these facts in mind, how do we explain the NO decrease in water loss (almost 0) when my solar cover is on at night??? Just the other day, I was too lazy to install my solar cover, and it dipped down to 54F (my pump was off), and wa, la, I lost almost a half inch in water level. There was no loss in water level during that same day (it got up to 80F)(the pool was at 88F since I have a heater).
 

MikeInTN

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May 27, 2007
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Middle Tennessee
donaldm823 said:
duraleigh said:
Evaporative loss is normally greatest when the temperature/dewpoint spread is the widest.....mid-afternoon on a normal, clear day. Wind (mixing of the atmosphere) is a significant contributor.

The "steam" you see (usually at night and early AM) is actually condensation. The air temp just slightly above the pool water warms a little and is able to accept more water vapor (gaseous). As that tiny layer of warmer air rises, it is quickly cooled by the surrounding atmosphere and becomes totally saturated....producing condensation (wherein the water vapor returns to it's liquid state).

You do not see the "steam" (condensation) in the daytime because the surrounding atmosphere has a wider temp/dewpoint spread and can accept far more water in it's gaseous state. The greater the temp/dewpoint spread, the more evaporative loss occurs. Those of you living in the desert Soutwest in that low relative humidity can attest to that.
Your explanation sounds real "official/technical" to me, but condensation means my pool level should rise-which in fact it does not-just the opposite. But my solar cover comes off every day at 1200 and back on at 1800. The only time my water level goes down is when I do not install my solar cover at night. I also run my pool pump ONLY during the day. With these facts in mind, how do we explain the NO decrease in water loss (almost 0) when my solar cover is on at night??? Just the other day, I was too lazy to install my solar cover, and it dipped down to 54F (my pump was off), and wa, la, I lost almost a half inch in water level. There was no loss in water level during that same day (it got up to 80F)(the pool was at 88F since I have a heater).
The condensation is still airborne, so your pool won't rise at all. It's no different than fog, basically. For your pool to steam off water vapor, your water would have to be around 212 degrees F, or you'd have to live in a vacuum.

I would guess the reason you don't see much evaporation during the daylight hours is that you have the pool uncovered for 6 hours, and covered back up for 18. To prove/disprove, get really, really lazy and leave it off from 0600 - 1800 or till sundown, and see how much you lose.