Hi there. We currently have a pressurised filter with UV but it doesn't seem to be big enough to stop the pond water from going green.
Can I either 'daisychain' two pressurised filters together or can I have the pressurised filter feeding into a normal gravity fed filter with just some foam and bio media in it to give the water a bit more filtration?
Or.....Should I give up and spend out on a bigger filter?
You can daisy chain pressurized filters.
You can direct outflow from the pressurized filter go a "gravity fed" filter or anything you like. Wouldn't actually be gravity fed, it would be pump fed, but I get the idea.
And you can give up and buy a bigger filter.
All common options. Also unlikely to clear your water. Ponds do clear on their own so while doing all this it could happen to clear and of course whatever you did last would get all the credit. Which is why there are lots of crazy solutions online and a bunch of people swearing by them. They saw it work with their own eyes!
Another option, and one rarely taken, is to figure this out.
UV is 100% effective when sized, installed and maintained correctly. Therefore, if your pond is still green it is because one of those 3 things isn't correct. Buying more and more UV units could fix a sizing problem but how the second is installed matters too.
Adding a second "gravity fed" filter. Bio media is used to house bacteria that convert ammonia into other stuff...it's a whole deal. Point is it has nothing to do with green water. Online people read "bah bah filter bah bah clean bah bah" and boy oh boy is it ever repeated all different ways. And again, ponds do clear, so lots of people "see" that their filter works.
Foam...good old foam. Was used a lot in pond filters a few decades ago. This can be thought of as a mechanical filter which is what most people think of as what "filter" means. Catches and traps stuff. Maybe coffee filter comes to mind? Can also be thought of as bio media but that's not true at all. In your case mechanical would be the interest. Couple of problems. A filter that could trap green water algae would clog very fast. Say in an hour. It's cool as heck...it clogs, you clean it and see, with your own eyes, all the green being removed. Works great. Then you clean it the next hour, the next...then you get sick and tire of cleaning the filter. But more importantly most foam is not dense enough to catch many algae cells. Most get thru. The foam looks really dirty, you "see" lots of green being washed out, must be working. But the cells that get thru are the smallest and youngest and healthiest. The kinds that reproduce fast. Faster than foam can stop them.
Skippy filters are a very old way to filter pond. Long proven to have little ffect on green water or bio or clarity in the beginning and less as time passes. But they do have some very appealing features. Super fun to build. They're just a little complex looking so a person can feel proud without having to do much research. A little expensive so it feels like it should work while not so expensive to put people off. But I think their best feature is that it takes just about the same amount of time to build one as it takes for a pond to clear on its own when it's so inclined. So there will always be champions of the Skippy.
A Skippy filter and a pressurized filter are basically the same type of filter. If either isn't cleaned it will become a waste tank.
TT filters on the other hand have been tested and proven to be about 10 times better at bio than Skippy. May clear green water although this is tricky and not proven. Cheaper and easier to build. Can look much better.
Not suggesting what the best course would be for you...don't know anything about your pond.
