Water evaporation

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We use the 10 percent threshhold as our standard and have an auto fill system tied to our irrigation system which draws from a lake, so if the pond loses less than 10 percent a week, we include that volume in our water change at the end of the week. Could be a leak, water discarded during a filter flush, or could be evaporation but it doesn’t matter which if it’s all under 10 percent per week. But it would be useful to know approximately how much evaporation is occurring. Sounds like the math is too hard.
 
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Sounds like the math is too hard.

In general, yes. Math IS too hard. But I think in this case there are just too many variables to come up with a formula that works across the board. There are definitely evaporation rate tables, but how do you factor in a sunny pond vs a shady pond, or a splash waterfall vs a trickling stream. Or a pond full of plants vs one with few plants. Windy vs calm. High humidity vs low. Lots of factoring. And - math=hard.
 

addy1

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I am losing around 3-4 inches in 3 days in the hot tub pond. No waterfall, no pipe leaks just evaporation. The big pond I am adding water every day, a hour of input to refill. If I don't it drops by 6 plus inches in a few days. The bog, the plants, the surface area, the heat, I lose this much every summer. Never a leak.
Hard to buy evaporation at 6 inches.
 
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Hard to buy evaporation at 6 inches. Our pond drops about 3/4 to 1 1/2 inches a day but I know there are a couple of leaks in our 4 waterfalls. Does someone know how estimate evaporation, maybe as a table of values based on
Square footage and water temperature at different humidity levels? It’s probably a calculus equation, but a set of tables would work.

Don't buy it either, saying a pond can evaporate in one week if the pond is 42inch
 
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A lot of it depends on your waterfall. You would be amazed how just a tiny overflow can drop you water level significantly. I just redid my pond and I am not losing near as much water as I was with my old pond. I changed my waterfall to drop more directly into my basin rather than flowing from further away then dropping in my pond. I was losing about an inch to two everyday before i redid my pond. Now I only lose an average of a quarter inch. I even have more surface area. I would inspect my old pond and swear I didn't see where water was leaking out because it was slow but that slow leak over 24 hours adds up. Here are some pictures of my old waterfall and my new one. The old one dropped gradually and had more of a chance to spill off to the side where the new one drops straight off and has more area that is in the basin behind it.
 

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Don't buy it either, saying a pond can evaporate in one week if the pond is 42inch

We have a natural pond near our house. It’s about 4 feet deep and an acre in size. It routinely dries up completely at least once per summer. And it will happen in a matter of days. A garden pond would slow down evaporation once the water level was too low for the pump, but it could definitely evaporate completely given the right conditions.
 

sissy

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I had a plant with roots that grew out of the waterfall pond and it was sucking water over the side.Amazing what roots can do .Now I trim the roots often
 
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I find evaporation one of the most interesting aspects of a pond.
Low humidity = high evaporation rate no matter the temperature. -40c to +40c. Even ice evaporates.
High evaporation = temperature reduction.

That's why pond covers work so well for retaining heat in the winter - they increase the humidity which in turn reduces temperature reduction. A pond cover can be man made or natural ice.

Plants will increase evaporation when their stomata are fully open ( stomata are small openings on the plant leaf surface to aid in gas exchange). What conditions dictate fully open depends on the plant species.
It always gives me something to think about, anyways.

.
 
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I should mention that in areas with high temperature and high humidity, the options for cooling a pond are limited. (@Mmathis )
Either shade or a deeper pond are the only realistic options for cooling.
 

Mmathis

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I should mention that in areas with high temperature and high humidity, the options for cooling a pond are limited. (@Mmathis )
Either shade or a deeper pond are the only realistic options for cooling.
LOL, yes, 1/2 of the shade sails are already up, and at 3.5’-4’, can’t go much deeper! Ah, the joys of living in the hot, humid South! Yesterday our heat index was 106F.....!
 

Mmathis

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106f = 41c.
Holy smokes @Mmathis , I don't know how you do it.
:)
That’s the HEAT INDEX, not the actual temp. Well, you stay indoors a lot! And hydrate! Pay the electric bill, and hope there are no power outages — thank goodness we got a completely new HVAC system 2 summers ago. Oh, and around here, you don’t see many dark colored cars!
 

sissy

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it is only 11:30 am and already over 90 degrees and still no rain .Humidity is at 82 %.Please send me some rain someone
 

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