The Pond Project – Part 2

The water had completely drained out overnight. All I had accomplished was to drown some earthworms and I felt terrible about that. So I figured that I just had not used enough Bentonite clay.

The farm store was not open on Sunday so Miss Mercy, kind soul that she is, picked up another 200 pounds of Bentonite for me the next day since it was kind of on the way home from her job and the next Saturday the weather was perfect. So I put all four bags and raked it into the dirt and filled the pond again.

Fingers crossed – looking pretty good

Drained again! What in the world is going on?

Well with more internet time I found out that there are actually two different types of Bentonite clay: Bentonite Calcium and Bentonite Sodium. Turns out most farm and garden store sell Bentonite Calcium. Bentonite Calcium is a soil amendment to stiffen your soils and remove heavy metals but does not expand. I found out I could put a ton of it into my small pond and it’s not going to do a bit of good. If you want to seal a pond or dam you need Bentonite Sodium that will mix with the soil, expand and seal.

Because I have the best wife ever (they call them your better half for a reason) Miss Mercy did some research, made some calls and found a place fairly nearby that carries Bentonite Sodium clay at a reasonable price. So a road trip is in the offing and hopefully that will do the trick.

The Pond Project – Part 1

So for the better part of the summer I have been hand digging a new pond in our yard. Miss Mercy and I have had many discussions about how deep it should be, what it was going to look like, should it have fish, should it not have fish, etc. We finally determined that about 15 feet in diameter and a gradual slope down to about three feet deep or so would fit best in the space.

I started roughing out the hole I was going to dig and then built a hugelkultur type berm behind the area, to create a wind brake and give us a backdrop for the pond.


In case you are not familiar with hugelkultur it is basically a mound of dirt covering a core of wood. One of the best places I’ve found to read up on hugelkultur is at the Wheaton Labs Hugelkultur Forum. It would be best for the mound if I was able to pile it six feet or taller, but, because we live in the city, I tend to keep things lower so they don’t protrude over my privacy fence and make my neighbors wonder what I’m up to (I actually have great neighbors, but not everyone driving by might be as understanding, so lower it is).

Pond with hugel berm and hugel mounds

We had been pondering how to seal the pond and since I’m trying to keep things simple and less toxic we really didn’t want to use a pond liner so we researched other ways to seal the pond. The biggest problem I have is that we are blessed with great soil in our yard, drains well, with very little clay – excellent for growing things, horrible for holding water in a pond. We finally settled on Bentonite Clay. Bentonite is a clay that expands by 15 to 20 times and bonds with the earth to create an area that will hold water. Fantastic news! So on advice from a co-worker who is familiar with the process and after some online research I got 100 pounds of Bentonite from a local farm store, mixed it into the soil and filled my pond with about 3,000 gallons of water. Everything looked wonderful. Here’s the picture:

Pond filled up


So the next morning I was very excited to see if the water had cleared up.