uv lights.

[addy1]

I my opinion a UV light is a must have option to have if you want to have clear water all the time,

I disagree, I do not have a UV light never have green or cloudy water, only filter with pea gravel and plants (bog type filtration)

This is the pond clarity with the bog just starting to grow this season.

This is mid summer, 5 foot deep area, my ponds are full sun

 

[Lisak1]

I also don't think a UV helps get things back in balance. I look at algae growth as a symptom. It's telling me something about the condition of my pond. If I use a chemical or a UV light to clear the pond, that only deals with the symptom - it doesn't get to the root cause. And at the same time, I believe it throws something else out of whack - kind of like taking a medication that deals with one symptom but leaves you with a side effect that's just as troubling. If you have an overloaded pond, I would address that. If you don't, eventually nature will.

 

[Ray G]

Interesting thread! I wonder what the differences are in the ponds that need an algae cure and ones that don't have algae. In my case I have to contend with over 100 degree F summers (up to 45C) recently. And full sun. No algae and no chemicals and no UV filter! I have a fairly large pond with 12 fairly large koi in it. biggest Koi are about 18inches long. I have a large gravity fed filter with about 4 cubic feet of bioballs and actively growing plants. I end up with very low levels of nitrogen in the water so it cannot support algae growth. No surface runoff can enter the pond either. my main waterfall is pretty active and I have a secondary one at the other end of the pond. I have no mechanical filtration (sponges or foam etc). my water is so clear you can see sand grains on the bottom of the pond. I think importantly in my set up the water passes through the filter very slowly as it is a big cross-sectional area for the water flow. It is not pressurised at all.
As I said at the start an interesting discussion (really important one as well).