Originally Posted by
Mendip
The waterfall provides some circulation and aeration but not nearly enough. My plan last year was to get one of those paddle wheel things and anchor it in the middle of the pond but as I said, once the problem was over (ie, most of the fish had died) my attention got diverted. Fingers crossed we don't get another major algal bloom this year.
I have thought about UV filters installed in the intake pipe beneath the waterfall... but as you say it's a lot of work. This pond was only ever meant to be a small hobby and a means to pass time and catch a few fish. We've tried many floating plants but all have been eaten by the fish, and if not eaten, the pla nin hollow out the soil from the pots to make their nests. The only plants that seem to survive are bull rushes that I sneak out of a village pond not far from us. Even with those I have to cover the pots with wire netting to stop the fish nesting.
When I get time over the next couple of weeks I plan to pump out the sludge which I guess is accumulated fish shit and also around 50% of the water and replace it with fresh. I'd like to wait until rain is forecast but it's not a good time of year for that. I'm hoping that annual sludge pumping and a paddle wheel thing (if I can find one) will be enough. A solar powered paddle wheel would perfect if there is such a beast. I want to avoid using any chemicals, although something to decrease the pH when we get algal blooms may be a good idea.
Sadly I dumped a couple of cubes of gravel in the bottom of the pond before filling with water as I thought that would help create a good habitat for beasties and things, so complete cleaning won't be easy.
My immediate problem is how to get rid of the pla chon. I stupidly introduced four of them from the market a few years ago as we were getting overrun with tilapia fry. These must be big fish now and have bred (I've seen small pla chon around the margins). I think there will also be pla duk to 10kg in the pond... I caught one at 5.5kg but that was three or four years ago. Maybe draining, cleaning and starting again is an idea... but an awful lot of work.