First off, many thanks to all of you; as I have been reading your great advice here on pond leaks. It has helped me tremendously, but now I'm stumped.

I live in Richmond, VA. I have a Koi pond in my back yard with 15 small to medium koi. The pond consists of a lower pond that is a half-oval, 14' x 8' and about 24" deep at center. There is a 12" shelf around the outer ring. The upper pond is a 3' x 3' x 3' deep pebble filter that waterfalls down to the lower pond directly (no stream bed).

I have a 2400 gph mag drive pump that pulls water from the lower pump and pushes the water up through the pebble filter. The pond has been trouble-free for the two years I've owned the house. It was installed in 2000, and I have no records from the installation.

About three months ago, the pond started dropping about 3/4" per day. I used the advice here to isolate the upper and lower ponds and the plumbing. The leak is in the lower pond.

Last week, I let the pond keep leaking down, thinking that the water level would stop dropping at the level of the leak. Well, I got down to 7" and still dropping so the leak is likely on the floor of the lower pond. I can see why some of you describe this as one of the most frustrating experiences! I spend a good 10 hours crouched in the pond feeling every square inch of the liner looking for a leak. I tried watching disturbed sand and the milk-drops trick to no avail.

I come home from work yesterday and see that the water level has dropped 3" and paniced. I look down and see that about 20% of the liner on one side has swelled up with displaced water underneath it, I must have disturbed the escape path of the leak or made the leak worse.

My questions to you experts is this: How can I make this most-recent event work in my favor? Would you guess that the leak is on part of the displaced liner? Or is the leak near the displaced liner and the water that's leaking out is finding it's was to the displaced liner?

Any ideas are greatly appreciated!

Thanks,
Dan

Good news is that leak can't be at the bottom. The bad news is that the 3" leak can't be in the lower pond. If the lower pond was the leak the liner would not lift. How did you determine that the leak was in the bottom pond? Is the pond bare liner or is it rock and gravel? Is there a skimmer on the pond?

Mike

On two consecutive nights, here's what I did. I wanted to isolate the ponds from each other and the plumbing. I closed the gate valve at the top pond so no water could siphon/drain back to the lower pond. I removed the filter cone from my pump and tightly screwed in a PVC plug using teflon tape. In that way, all they are isolated. The next morning, I was down 3/4" of an inch.

Just to make sure, I did it again the dollowing night with identical results. Now I'm really confused.

I scoured the bottom for the leak and got down to just 8" of water.

I then refilled on Sunday and called a pro, who won't be here until mid next week.

On Wednesday, the liner began lifting and the water level dropped 3". Same on Thursday, and I added more water to make sure fish were okay.

Today, 50% of liner is lifted. Going to put some weighted buckets on the bottom, with soft towels underneath to hold liner down.

Any ideas? What can I do until the pro arrives?

Thanks!

Dan

I'd forget about trying to weigh down the liner. It takes a tremendous amount of weight to stop a liner from floating. You're more likely to put a hole into the liner, which doesn't have one. If it did have a hole water would flow from under the liner thru the hole and into the pond.

As you're finding out a leak is difficult to find. Helping to find a leak in another person's pond with just some text...impossible. For the best possible help post a few dozen pictures documenting your pond, the boring stuff. Be prepared to post more pictures for more details. Number each picture so they can be referred to. Unfortunately this forum's software doesn't make that easy at all.

I can't write any more...tooo many pop up ads...can't edit...sorry...good luck

The events of the past few hours have certainly shown me that you are both correct about the source of the water. I don't know what the heck I thought I was doing with my testing, must have read my yardstick wrongly. At daybreak tomorrow, I will be digging out a cubic yard of pea gravel into two large trashcans and get to the manifold at the bottom of the filter pond.

No doubt, it's leaking at up there.

All of my plumbing is now exposed, so that's not it.

It's leaking like a pig now when the pump is running. I can't even get the waterfall to flow with the pump on, put I but my hand in front of the pump and it's pulling water, so all that water is getting underneath.

A close look with a flashlight tonight showed damp ground all around the upper pond at the base of the dirt build-up. This explains a lot of things - wet vegetation around the pond, a shrub that died where the water is accumulating, and the waterfall has been a bit less powerful and tonight it"s just a trickle (pump off now).

Big question: I've always run my pump 24/7. Will the fish be okay for 24 hrs with no aerating waterfall, or should I go out and buy a fountain or take my oxygen tank from my welding kit and bubble some O2 up?

I will post some pictures tomorrow so you can all see my leak.

I would not think that it is the manifold at the bottom of the filter. Depending on how the piping goes into the filter would be where I would look. The first thing I would do is close the knife valve at the top pond and turn the pump on. If the pump is still sucking water in the problem is between the pump and the valve. If it is not there I would leave the valve closed and see if the water level in the top pond goes down. If it doesn't go down than the leak then the leak is in the top of the upper pond or waterfall.

Mike

I dried it all out, cleaned and scrubbed the area with solvent and applied a thick circular patch. The liner was as thin as a trash bag at the hole area. Something must have been gitting the area for years. It was right near an exhaust port on the manifold.

Since I already had my plumbing exposed, I simply cut it, put on a 90 and a 5' stick of PVC and was able to keep the pond circulating while I did the work.

I re-filled the pond to the max and the weight has pushed almost all of the liner right back into shape, to the point where there is water around the pond soil.

Thanks you all very very much! The hint that the water leak couldn't be in the lower level sealed it for me.

Warm regards,
Dan

While there, I made a new manifold that wont pack up with pea gravel.