One more question. At some point in the past I read something about rocks in the pond causing or making the muck worse.
So I got the rocks out of the water as much as possible.
I have searched and I can't find the post again. Everyone else has rocks all in and around their ponds. And now I'm adding gravel and plan to finish around the edges with rocks in the water.
Apparently I mis-read or something - maybe it's the type of rock?
Does anyone know what I might have misunderstood? Is there anything I need to know about rocks in the water?
Thanks
There are definitely pros and cons. Here's a thread that discusses the issue in depth:
https://www.gardenpondforum.com/threads/pros-and-cons-of-rocking-the-interior.31265/#post-495244
I started out without gravel in my pond, but that's only because the gravel that I have is full of pointy bits and flint, and so has to be washed and filtered one handful at a time. So I'm going very slowly, filtering it whenever I have a free moment and tossing a few handfulls into the pond. One reason I like a lot of gravel is that it provides a tremendous amount of surface area on which nitrifying bacteria can grow, thus cleaning the water and making it safe for fish. Some people even add perforated PVC pipes under the gravel, through which the water is pumped (sort of an "in-pond bog filter").
But I think whether to add rock depends a lot on the type of filtration you have. For example, if you add a bog filter (even a small one) and your skimmer is working well, then the amount of muck will be minimal. You definitely have enough rock in your existing waterfall to create a beautiful overflow from a bog. You'd want to think "horizontal" rather than vertical -- making a lined depression with sides high enough above the pond to allow you to overlay the bog liner over the pond liner with no fear of leaks.
@poconojoe has a great thread showing how he built his bog. You can use your existing waterfall rocks to line the bog and build a natural looking overflow into the pond.
If the skimmer doesn't seem to be doing its job, instead of buying a new one, you could just create an intake bay. This is a very simple DIY, especially if you have enough extra pond liner to enlarge the hole where your skimmer currently sits. If you don't, you could use a rubber tub located inside your pond to do the same job. The main idea is that you'd have the pump located inside the intake bay, with water being pulled in through a narrow opening near the surface. Ideally, the tub/bay should have a false bottom. I used upside-down milk crates of mine, shown below:
The garbage bin in the photo houses the pump and has slits carved around one side near the bottom, to force the water down toward the bottom of the tub / bay.
Then, on top of your false bottom, you add some gravel, put the pump inside the container (with a hole near the top for the plumbing) and voila! Instant skimmer!
Another reason to add rocks to the pond (and not just around the edges, is a purely aesthetic one; the pond looks more natural, and you can add little planting pockets among the rocks by pouring in a bit of gravel. Here's a recent photo of my pond in progress, which shows the areas that have been rocked in vs. those that have yet to be rocked in.
Big difference! The work is going slowly, as I'm doing it on my own, and as a 60 year-old granny, I'm less fit than I once was! But you can definitely see the advantage of having the edges fully rocked in.