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  1. #1

    Expected evaporation rate in November?

    Hi all

    I have recently finished constructing a basic 7200L pond with liner, which has a surface area of 2mx3m. I am finding my water level is dropping by about 5mm a day.

    Can I expect a small amount of evaporation at this time of the year (late November)? or do you think this is a small leak?

    Thanks in advance



  2. #2
    Extreme Koi Member Rank = Mature Champion pip895's Avatar
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    Yes I think you have small a leak - unless you are running a drum filter I suppose but that would be rather obvious. Do you have a skimmer? I just mention it because they are a common source of issues.
    Last edited by pip895; 22-11-2017 at 09:57 AM.
    6000g in ground koi pond
    +3000g lily/Anoxic pond attached
    29 koi (40 to 65cm)
    Bottom drain, Mid water & Skimmer to Drum
    JBR boichamber->Blue eco 500 pump ->below surface return.
    Blue Eco 240 -> Large MB -> Waterfall -> Planted Anoxic pond (25 baskets)

  3. #3
    Ah dam! No I don't run a drum filter, I have a bay filtration setup but no leaks visible. No skimmer either.

    How on earth do you find a leak that small if its on the base of the pond (which is where it is most likely to be)

  4. #4
    What is the water temperature ? If it's a lot higher than ambiant then it will evaporate quicker.

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    Extreme Koi Member Rank = Rokusai AlanF's Avatar
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    Quote Originally Posted by willshill View Post
    Hi all

    I have recently finished constructing a basic 7200L pond with liner, which has a surface area of 2mx3m. I am finding my water level is dropping by about 5mm a day.

    Can I expect a small amount of evaporation at this time of the year (late November)? or do you think this is a small leak?



    Thanks in advance
    Put a bucket of water next to pond and monitor the level - if it drops the same then you should be ok. I thought my pond must be leaking when I first filled it but am sure now it was just evaporation losses.

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  8. #6
    Great idea! The water temperature at night must fall at a much slower rate than the atmospheric temperature so evaporation must occur? Then again a bucket of water will also drop in temperature much quicker than the pond will so this may not be an accurate test... I will however try this.

    Many thanks!

  9. #7
    Extreme Koi Member Rank = Nanasai Fishplanetkoi's Avatar
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    Just add a trickle top up to the pond at around 20% a week, and at 5mm loss a day, you will never have to worry about it. It will keep the pond at its full height and also refresh your water each week. You may have to fit an overflow to your multi though, which is a simple fix.

  10. #8
    Quote Originally Posted by willshill View Post
    Hi all

    I have recently finished constructing a basic 7200L pond with liner, which has a surface area of 2mx3m. I am finding my water level is dropping by about 5mm a day.

    Can I expect a small amount of evaporation at this time of the year (late November)? or do you think this is a small leak?

    Thanks in advance
    Try to look at this web site calculation formula - I found it - and the others they have there - quite helpful:

    https://www.gardenpondforum.com/thre...ur-pond.21500/

  11. #9
    Deleted duplicate post.
    Last edited by Manky Sanke; 22-11-2017 at 09:25 PM. Reason: Duplicated post

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  13. #10
    Quote Originally Posted by willshill View Post
    Great idea! The water temperature at night must fall at a much slower rate than the atmospheric temperature so evaporation must occur? Then again a bucket of water will also drop in temperature much quicker than the pond will so this may not be an accurate test... I will however try this.

    Many thanks!
    The bucket test is a good way to tell whether the level drop is caused by evaporation or a leak. It's a common method to test a swimming pool for leaks and works well. The only refinement I would add is that the bucket should have something heavy in it such as a brick and it should be suspended in the water so that the level of the water in the bucket is just below the level of water in the pond (hence the brick).

    That will ensure that the water in the bucket stays the same as the pond temperature. All you need to do is use a bucket that won't harm the fish if they bump into it and fix it in a corner so that they can't change the level by splashing or tipping it.

    Something you could try if you're worried that the koi still might injure themselves on the bucket is to wrap it in bubble wrap. If you don't have any bubble wrap you could try stealing a fluffy towel from the airing cupboard, rinse it to remove any fabric conditioner and wrap the bucket in that, but be warned, if you get caught, this idea carries it's own risk of injury, not to the koi, but to you.

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  15. #11
    Moderator Rank = Supreme Champion Feline's Avatar
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    Quote Originally Posted by willshill View Post
    Hi all

    I have recently finished constructing a basic 7200L pond with liner, which has a surface area of 2mx3m. I am finding my water level is dropping by about 5mm a day.

    Can I expect a small amount of evaporation at this time of the year (late November)? or do you think this is a small leak?

    Thanks in advance
    To me that sounds excessive. My pond does not evaporate in any way you could actually measure at this time of year. If you left a glass of water out in the garden (not open to the rain) you wouldn't expect it to dry up any time soon in November. It sounds to me like there could be a leak.

    What do you have in the way of pipes and bottom drains?

  16. #12
    Yep Lara,

    That was my thinking, at this time of year, 5 mm per day is far more than I would expect from evaporation.

    In the swimming pool trade there is a rule of thumb "anything more than ½ inch a week is a leak". Bear in mind that swimming pools are usually heated to about 30°C, they are used in summer when the ambient temperature is a lot warmer than now and that splashing contributes to any level drop. A drop of ½ inch a week is 12.5 mm per week and 5 mm per day from a pond is 35 mm per week which is nearly three times what a warm swimming pool in summer would lose.

    The bucket test is what I would call the first step in proving that it definitely isn't evaporation.

  17. #13
    Extreme Koi Member Rank = Mature Champion pip895's Avatar
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    Leaks are such a pain!. I am struggling with a leak myself at the moment. After several months trying to work out where it is and make various repairs to areas I thought might be causing the issue. I am now going through the process of working out if it is something I can live with. I have an automatic top-up with a water meter attached. Yesterday I had to add a total of 500ltrs to top the pond which is acceptable but only just. A 10% water change per week would equate to ~580ltrs/day. However it rained last night so I'm not sure if the true figure might be higher.
    6000g in ground koi pond
    +3000g lily/Anoxic pond attached
    29 koi (40 to 65cm)
    Bottom drain, Mid water & Skimmer to Drum
    JBR boichamber->Blue eco 500 pump ->below surface return.
    Blue Eco 240 -> Large MB -> Waterfall -> Planted Anoxic pond (25 baskets)

  18. #14
    Extreme Koi Member Rank = Grand Champion Andre Asagi's Avatar
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    ^ Likewise but mine is much worse. I will start my own thread rather than detailing on someone else's thread but i'm almost at the point of throwing in the towel and contacting someone like Maxine Grundy and asking them to come and get the fish.

  19. #15
    Extreme Koi Member Rank = Adult Champion bowsaw's Avatar
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    does sound like a leak, though i have a tank that needs topping up at least 5% of its total volume a week due to evaporation loss. though no wind as such to drive off the water, it is running at 6 oC above current room temperature, so you can in some circumstances get more evaporation than you would like,

    how far does it drop if left for a week or more with out being topped up?
    the slow pond build thread

  20. #16
    I'm new to ponds but given the sizes you mentioned that would be 30L of water per day and I can't see that just being evaporation.

    When I inherited my pond (came with the house) I had a similar leak, I had to go and buy a huge swimming pool to completely empty the thing and found 2 splits in the liner that were literally 2cm long, I repaired the two splits and transferred everything back and it was still leaking, so I just ended up replacing the liner as trying to find any more splits proved extremely hard.

    Hope you track it down and get everything sorted out man, just don't make the same mistake as me and put everything back without thoroughly checking everything.

    IMG_20170822_103253.jpgIMG_20170822_130537.jpg

 

 

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