Hi all, hoping someone with a bit more experience can help me here! We bought our first house back in August of last year, have spent a ridiculous amount of time decorating and have only just turned to the garden this spring. It has three ponds - two raised (like in planters) ponds, and one ground-level pond, all a bit overgrown and lovely - but we don't need three ponds!! My grand plan was to keep the largest pond (which has lots of fish, and I quite like that) and drain the other two to create more room for roses in the larger planter and grow some veggies in the ground-level one.
Yesterday I roped OH into clearing and draining the smaller of the raised ponds - however we noticed that the water level had only dropped about 6" despite us draining water for about half an hour... and then I noticed that the larger pond had lost about 6" of water! We then filled the smaller pond back up (with normal tap water as we weren't thinking - happily the fish seem quite hardy and we haven't had any deaths yet, I've checked!), and lo and behold, the big pond also filled back up. So clearly they are linked under the decking, somehow. We pulled up a bit of the decking, and couldn't see any obvious connection - my feeling is that when the whole pond/decking area was built, the two ponds were joined underground, I suppose to ensure that they both had water at all times.
So, I guess my question is this, short of draining both ponds, which would probably upset the lovely fish in the biggest pond and blocking the connection, is there a way to plug the hole in the smallest pond (we do know where it is - managed to poke a stick down it!) while it is still full of water??
And to make matters worse, we were going to drain the low-level pond, that cannot be connected, and then found there was an enormous lovely frog living in it, so clearly we cannot drain the pond until the big pond is sorted and he can be rehomed!!!
Any advice gratefully received - I've googled and flicked through my gardening books but no idea how to tackle this one.