what do you use to seal clay?

Ashland City, TN

I’m sure this has been answered many times so if you can send me to a “thread” that talks about this topic that would be great.

I have some koi that I have raised in a 3 foot deep, 4 foot circular lined pond for the past 3 years. Time to enlarge. I have researched several types of pond linings. I want a light one so I can see the fish. I was thinking concrete but that is a lot of work on my part so…having a back hole come in and digging out a nice size whole and sealing the “clay dirt” – that is what we have around here. Now…what do you seal a pond like that with so the water won’t leak out? I have heard of “lime” (? I think that is what she said) and then there was some kind of clay you can have brought in…it starts with a B – like betadine clay or something like that. Thanks for any suggestions???

springfield area, MO(Zone 5b)

benzonite, I think. But I have heard that it is kind of pricey. I have never looked into it myself.
The best thing is a black liner. The black color creates the illusion of depth, making the pond appear deep, even it is not.
Do not put gravel on the bottom, it is impossible to clean. I have never heard of putting lime in anything in the pond, I think that would be bad for the fish? If you use concrete, it has to cure a long time and then maybe be sealed to keep stuff from leaching from it.
Unless you are using a liner, I'm not sure there would be any fool proof way of getting it to be water tight. Even the clay will absorb and leak a little I would think.

have you actually visited other ponds to see what they look like? I don't think a light colored liner would show the fish very well. IMO I think the fish would look washed out on a light color.

Ocoee (W. Orlando), FL(Zone 9b)

I use the black liners, they make the colors on the fish pop. I agree, no stones or rocks on the bottom, it's a breeding ground for bacteria. Along the top edge for decor and to hold the liner is fine.

noonamah, Australia

The clay you're thinking of is called bentonite. It's usually incorporated into the soil in the bottom and sides of the pond. You can put it down as a pure layer and then soil/gravel/sand over top. You should be able to google it to get a lot more information, distributors and price.

Ashland City, TN

Great...thanks for the info. I think my main problem would be finding the bentonite in this area to have it brought in - making the price much higher. As for a liner...I'll have to check out the difference in prices from the pet store up the road (they sell it by the big rolls) and on-line prices. Guess I may as well slow down and do it right.
Thanks again..

springfield area, MO(Zone 5b)

buy a liner with a thick mil count, most pet stores sell cheap thin ones, and they will not last nearly as long.
I bought one that was I think 60 mils. It is really thick.

Holland, OH(Zone 5b)

If you do go the clay route it means no plants or vegatation in or around the pond. Muskrats like to just tunnel under the waters egde and den. Plant roots can pierce the clay and drain the pond. Some clay ponds have a geotextile fabric or geosynthetic clay liner. See the Link. Also, here's a link about clay ponds, problems and remedies.

http://www.geo-synthetics.com/Geosynthetic_Clay_Liners.html
http://www.cnr.vt.edu/extension/fiw/fisheries/pondslakes/leaking.html

Clay ponds are all together different than EDPM lined ponds. Much, much trickier to manage and maintain.

The biggest problem is that they leak.

Cleveland area, OH(Zone 5b)

I am having the same issue. We have clay soil that holds water forever, so we thought we'd dig a hole and have a natural bottom pond. But, it loses about three inches a day. We have tried the bentonite route, but possible didn't put down enough.

My problem is the dogs like to get into the pond, and I worry about them tearing the liner with their toenails. we are actually thinking of a liner, then chicken wire mesh, then sur-wall on top of that.

noonamah, Australia

Bentonite is extremely fine and light in water. Any swirling will wash it away. That's why it has to be covered over with other layers. Any animals getting into it and stiring it up diminish its efficiency.

springfield area, MO(Zone 5b)

I have a 60 mil liner. It is REALLY thick. Thick to the point I found it difficult to work with.
Unless you have like huge dogs, I don't think their toenails would hurt it?
I designed my pond so that nothing gets in it. It is 6 ft round, and drops STRAIGHT down, so I never get animals in it. It is raised a foot or so, that saved some digging, plus, it leaves less 'bank' room for critters to access the pond.
You might think of some neat design fixes that would detour your dogs. Maybe you could even do a small 'pond' for the dogs nearby and train them to only use 'their' pond?

Cleveland area, OH(Zone 5b)

FrillyLilly, I have to laugh! I have one dog, but my four sons have five dogs, and when we get together, all the dogs come to visit! In addition, I have eight young grandchildren, and I want this pond to have a gradual slope, so it's not dangerous. The more I think about, the more I like the concrete / surwal solution. I just don't think anything else will do.

In the meantime, I wish I lived closer to scardiecat so I could barter all the bags of bentonite I still have.

Ashland City, TN

I have thought about concrete but dang the work (I have worked alot with concrete)...I did read a web site that said it is easier than alot of people make it out to be and the "plan" they showed did look easy - IF you consider laying concrete easy. What is surwal?

Ashland City, TN

about how much would I expect to pay for 60 mil of liner? What is a reasonable amount?

springfield area, MO(Zone 5b)

I found Ebay to be the cheapest for liner, and even with shipping.
Plus I was pleased with the liner. No problems whatsoever. I was leary of ordering something I couldn't see, but it was great.

Cleveland area, OH(Zone 5b)

Sur-wall is concrete with epoxy and fibers in it. It's what you skim-coat concrete block basements with to make them waterproof.

We've about decided on this: We're going to drain the pond, put down heavy construction plastic, then wire mesh - something heavier than chicken wire, probably like a rat wire. Then mix up the sur-wall like concrete and trowel it on. We'll use mason stain to color it a dark brown-gray, but maybe brush that on instead of coloring it through. We're thinking about an inch thick.

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