The 15000lt outdoor pond I am currently building will be equipped with waterfall pump and a filter for running this koi pond. Any suggestion on the capacity of waterfall pump/filter. Would it be sufficient if I just install the waterall pump and without the filter. Pls. enlighten me on this. I will be keeping 5 young (4inch) kois, would if be right if I add
mature ones too in the future as I worry the young ones might be bullied by the larger ones. Thanks once again for answers.

It took 9 months to achieve my goal because lack of time.
It’s new and improve. Ancient pond had no skimmer,waterfall, bottom drain, and no canopy. ,Air aerator,and it had one filter. It was about 1300 . . .

I need a large submersible pond pump for a 5000 gallon pond. Which brand is the most reliable. There will be about a 9 foot head(calculated using a 1″ output pipe). I want it run continuously and efficiently without clogging and with as small maintenance as possible.

The pond is deep because it has a pump which feeds a waterfall. I noticed a hole, near the top, about the size of a one pence piece/cent. It will be underwater when it is fixed. Can you tell me a method of repairing it? Thanks.