Double pond is leaking somewhere

[Tokenicole]

Hello everyone!
Still having the same issue as before but my husband and I can’t agree on a fix. I have a preformed pond that was built so that the overflow goes into a sluice that then overflow’s into the waterfall and the bottom pond which is also a preformed that was buried. The pump and filter are in the bottom pond but we had to move all of the fish into the upper pond because there’s a leak…somewhere.. it was built by a friend who has since passed and he used a bunch of stuff that was “around” like cementing the rocks and liner to the upper pond with Force Flex etc

So our ongoing issue is that the bottom pond loses a large amount of water and needs to be refilled regularly but we can’t find where it’s loosing water! Is there some type of special dye that won’t get diluted by the water? Or something similar that would show where the water is being lost? Thanks for your help! Toke

 

[GBBUDD]

shut down the filters let the water sit when the water stops dropping , there's your leak at that level.
plug your plumbing lines and see it the water drops .

 

[Tokenicole]

Yeah it doesn’t loose water when the pump is off and the top pond is supposed to drain over the waterfall but it’s angled weird (I asked in an earlier thread about drilling holes in the top so that it would replace the water faster) so now we’re trying to figure out if there’s a leak between the top pond and the bottom one that’s keeping the bottom pond from staying at a stable level….?

 

[GBBUDD]

one step at a time see whos loosing water if you pull from the lower pond push up to the upper pond there shouldn't be an issue with flow unless the overflow is too small