Is it safe to use Bitumen in my pond

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Bern.r@icloud.com
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Is it safe to use Bitumen in my pond

Post by Bern.r@icloud.com »

Hi, I want to seal the mortar at the top of my pond. Where the liner meets the slabs.
Is it safe to use a bitumen product? Will the bitumen affect the fish.
Any thoughts are welcomed.
Bern
Manky Sanke
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Re: Is it safe to use Bitumen in my pond

Post by Manky Sanke »

The short answer is, yes, any leaching from bitumen based sealants will be toxic and they certainly shouldn't be used in a koi pond.

You can paint the cement with a waterproof pond paint such as G4 if you wish but, if the cement line is of normal thickness and above water so that it only gets wet from occasional splashes or when it rains, then I personally wouldn't bother.

There is an old belief that cement is toxic to koi, that isn't true. Cement, or concrete, that is exposed to water will leach alkalinity into the water and high levels of alkalinity from large areas of exposed cement (or any other material that adds alkalinity) will raise the pH. Raising the pH may be harmful if it's allowed to significantly exceed about 8.5 pH but adding alkalinity may even be beneficial if the pH is low or the value varies due to low KH. In fact, adding concrete blocks somewhere in the pond (preferably where the fish cannot hurt themselves on them) is an old way to buffer a pond pH. It all depends on the alkalinity of the source water that is used to fill and/or top up a pond and on the amount of water that is changed as the whether a buffer is beneficial or not.

pH and the various forms of buffering along with their effect on fish is a complex area and I could write pages on the subject (I regularly do!!) so, if you want to know more, it may be better if you ask questions about your individual situation so that I can answer about what is specific to you rather than write a long post covering the whole subject.
Bern.r@icloud.com
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Re: Is it safe to use Bitumen in my pond

Post by Bern.r@icloud.com »

I really appreciate the response. I was just about to go and buy some bitumen paint and thought that I would check for a reply before I did. Thank God I did!
I will get some G4 as you recommend.
Thanks again.
Bern
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