excessive water loss in recirculating stream - but no leaks

[mogilenski]

I'm puzzled by my 23' long, roughly 10" wide burbling stream that seems to loose 1-2 gallons an hour. There are some 2" cascades but nothing splattering. I removed the rocks and pebbles and checked the soil below the pond liner - all dry. Ditto the area around the one seam. The water flows into a sump (also sound), and flex PVC brings it back to the top (no leaks at the backflow or union and otherwise a continuous run). I also checked the banks, making sure the liner was well above water line and no vegetation was conducting water over the edge. Unless I missed something, the water is not getting out...and yet, it is. What am I not thinking of? Is the water loss just from evaporation? (there's no significant plants drawing water from the stream) The weird thing is that the stream functioned fine for about a year, running during the day only.

I'm even puzzled now about what to do, apart from abandoning the project.

[perniciousviper]

Think we can all relate to a pond problem that seems to defy all logic! Have you physically inspected all along the flex pvc, even if that means digging it up unfortunately?

[mogilenski]

Think we can all relate to a pond problem that seems to defy all logic! Have you physically inspected all along the flex pvc, even if that means digging it up unfortunately?

Thanks for the thought and the sympathy. I have not dug up the pvc - the one piece I didn't disturb in the system. The pvc runs just below the surface parallel to the stream, so I would expect moisture of that amount to show up as damp soil or as a density of plant growth, neither of which were apparent. That might be my next move.

I also thought maybe just to put the whole thing back together again, running and monitoring the water loss very carefully. Occasionally problems 'solve themselves' just as mysteriously as they start.

[perniciousviper]

I had a skimmer leak that bugged me for six months after installation, nothing major but with a drum in the system and needing to maintain a steady water level, it eventually became a pain. After running for six months it sorted itself out, I guess the tiny hole causing the leak just got clogged, and it's been fine for a year or so now I guess. So fingers crossed you get the same result with yours, if you're putting it back together. You sound like you've covered all the obvious and not so obvious potential causes (dangling plants acting as a wick, etc) except that run of pipework, and even though you haven't detected wet ground, I'd be inclined to take a look as a last resort. Good luck with whichever option you go for!

[mogilenski]

Thanks perniciousviper. Yes, yes, living systems... Having come this far, I'll check the pipe.

[icu2]

I'm the first admit that I've never made a stream that doesn't leak to some extent. I'm just not good at it!
But even though I know I lose water, I rarely find a wet area or an obvious point where it is leaking. I've found
my water is very crafty.

To narrow it down I break it into sections. It sounds like you have a "pond less" stream/waterfall so, and I know you have
said areas are sound, but I'd test every section anyway. I'd start with the basin. Fill it up and let it sit to be sure it
doesn't lose any water. Next I'd hook up the pump to the top of the stream and then find a way to plumb a bypass
of the stream and run it directly back to the basin, testing all the pipe work. Let it run and see if any loss. Then I'd
take my bypass and move it up about half way up the stream and let it run from there back to the basin and let it
run and see if you lose water. At that point you've tested everything but the upper half so if all is good to that point,
you've narrowed it down to a much smaller battle.

Good luck with your hunt! I feel your pain and have been in the same boat several times.

[stevek]

for what it's worth, I've had 2 different leaks in my 20 year old stream. The first was a hidden hole in the liner caused by a chipmunk . He wanted to get from one side of the stream to the other, but didn't want to get wet, apparently, so he burrowed under the liner and then miscalculated and came up under a flat rock that was part of a waterfall. Since the hole was covered, I couldn't find the cause of the leak for the longest time. Eventually, I dissasembled the rocks and found the hole and was able to patch it. Then trapped the chipmunks to make the problem go away.
The second leak was caused by a slight dip in the liner on the edge of the stream that was partially hidden from view by an overhanging japanese maple tree. The soil on the outside of the liner had settled just enough ,and the edge of the liner had dipped, and water was running over the edge. I think the tree roots were sucking up the water as fast as it came out, so I never noticed any puddles or obvious water leakage. Once I figured this out , it was a 2 minute fix to add some soil and pull the liner back into position.