Bentonite for small koi pond?

[jskirwin]

Hello
I am in the process of digging a small (app. 40x30X3 (max depth -average 1')) pond off the deck of my home. The pond will be in clay studded with quartz. Looking at the cost of EPDM liners I'm wondering if Bentonite might be feasible. The problem is that I have never worked with the stuff before, and it seems more common in large agricultural ponds with gentle slopes rather than a classic koi pond. I would prefer to have the natural clay look of the bentonite rather than working to conceal the liner with rock.

Has anyone used this clay before on a small pond with near vertical walls?

Thanks,
JS Kirwin

 

[fishin4cars]

If you use it you'll probably rarely ever see your fish, The koi will keep it stirred up. that's why Breeders call them mud ponds because they almost always appear muddy and are almost never clear.

 

[jskirwin]

Good point. Glad I asked.

 

[j.w]

JS

 

[Waterbug]

I haven't used Bentonite but have had a clay bottom pond, and grew up knowing a lot of clay ponds. I'll just call them mud ponds. The finest Koi are grown in mud ponds, but yeah, never clear.

Straight sides would erode pretty fast, so even if you started with straight sides you wouldn't have them for long. The mud ponds we had were very gradual sides for the most part and they still eroded a bit.

 

[sissy]

have you checked out rubber roofing as that would be cheaper and really the same stuff .It also comes in bigger sizes and you can get it most times from a roofing company cheap if they are overstocked .I got a big piece for 35 dollars because the roofer just had it lying around and he was moving and new owners wanted all the stuff gone .He wanted 25 but he had several pieces and I took it all for 35 dollars

 

[jskirwin]

Yeah it looks like I'll have to go with EPDM. The pond is rectangularly shaped and is actually cut into the side of a small hill. I plan on using the same rock lining the pond to line up the walls where it cuts into the hill. At its height, the top will be about 3 feet above the water line, where I will have a waterfall in the corner.

I suppose I have to line behind all the rock, even the stuff not near the waterfall, right? Otherwise I will have erosion filling the pond with fine red North Carolina clay.

The prices of liners are scary. I'm figuring about $1,500 for liner/underlayment alone - and that may be conservative.

I knew this pond was going to become a money pit which is why I've waited 2 years to build it and almost skipped doing it this year until I dug my first shovel full. I figured if I thought any more about it, I'd never do it.

 

[Waterbug]

Yeah it looks like I'll have to go with EPDM.

I like EPDM a lot. But there are other choices, like reinforced polyethylene. Google "water retention pond liner" for more options. It's all about picking the liner that best meets your needs. EPDM is really just in the middle of the pack.

You can also Google "used billboard tarps" which can be used as a liner. Just a question of how long you want it to last.

Check out the weight of a EPDM liner for the needed size. You're in the neighborhood of 600 lbs. Doable for sure, but I wouldn't want you to be surprised.

I suppose I have to line behind all the rock, even the stuff not near the waterfall, right? Otherwise I will have erosion filling the pond with fine red North Carolina clay.

Generally you don't. Rain washing down a liner can still wash a lot of dirt (dust) into the pond. Normally a ditch is placed just before the pond edge so runoff goes around the pond. The ditch can be filled with rock so it looks like a hillside. You still want to control erosion of course. Drain pipe and geo fabric is sometimes placed into the ditch, depends on the grade.

The prices of liners are scary. I'm figuring about $1,500 for liner/underlayment alone - and that may be conservative.

If you end up with nice fine clay soil you sure don't need an underlayment if EPDM is used. No better underlayment than clay. Or there are many underlayment options. Blankets from Goodwill, newspaper, used carpet padding, used carpet, etc. Buying nice new underlayment is easiest and most enjoyable, but it does cost.

I knew this pond was going to become a money pit which is why I've waited 2 years to build it and almost skipped doing it this year until I dug my first shovel full. I figured if I thought any more about it, I'd never do it.

Doesn't have to be expensive. You can save a lot of money by doing a lot of research and making sure you build the pond you want. You may not need all the standard pond things if your goal is different from the standard.

 

[addy1]

Check out http://www.btlliners.com ppl 24, I have used ppl24 on my arizona pond and ppl36 on this pond, really tough stuff. I think cheaper than epdm