please help! pond draining problem

[Weirdness555]

Hi, we're having a problem with our pond, once every couple of months or so it empties. It's never completely emptied so our fish are ok, but its getting lower every time and we have no idea what's causing it. It does it at random, there's no pattern to hot days or dry periods, for a while it seemed to happen after heavy rain but I don't know if that's a real pattern or not.

The pond is roughly rectangular, wider at one end, it's about 10' long by 5' at the narrow end and 7' at the wide end, with a surface area of 60sqr', it's 4' deep at its deepest point, which is most of the bottom, with planting shelves. It's attached to a whole series of waterfalls, splashpools and streamways, but they're not running because we think there's a leak somewhere on the waterfall because when we run it we lose water so we don't run it all the time. There's a filter running in the pond at all times with a return coming in just above the water level to agitate the water and aerate it.

Please help, we're worried about our fish if this happens when we're not around to refill.

 

[HARO]

I take it this is a liner pond, not an earth-bottom one?
John

 

[tbendl]

How low does it go? And after it leaks, have you checked around any and all external hoses and pumps to see if the area is wet?

 

[Weirdness555]

Yes it's a liner pond, it drains to maybe a quarter of it's depth? I am away at university so I haven't actually SEEN it, but I'll check with my parents for more details.

 

[Weirdness555]

It's draining to about 18" deep now, and the pipes don't seem to be leaking. We think there must be some kind of hole in the liner at the bottom?

 

[addy1]

Since it is random, has anybody walked the waterways, the waterfalls, the streamways, the splash ways, looking for a problem?. Any "leak" I have had has ended up being a misdirect of the water in one of those.