Yes. A properly installed, maintained and sized UV is 100% effect against green water. 100% of the time. If water remains green it means the UV wasn't properly installed, maintained and/or sized.Alonso said:I am wondering if there is a way (through filtration and UV) to achieve clear water?
I'm going to take a wild guess that you don't have string algae? No stream or waterfall with string algae?Alonso said:My pond is pretty green with single cell algae
You raise a very good question. I'd say about 99% of people on the internet say reduced light and/or nutrients will clear green water. Millions of web pages say it.Alonso said:My pond is pretty green with single cell algae and I am thinking of building some sort of roof over it to avoid sunlight in order te get rid of the algae, but I am wondering if there is something I'm missing cause I have seen pictures of ponds with clear water that recieve direct sunlight.....
http://koiclubsandiego.org/library/green_water.phpWaterbug said:Yes. A properly installed, maintained and sized UV is 100% effect against green water. 100% of the time. If water remains green it means the UV wasn't properly installed, maintained and/or sized.
I'm going to take a wild guess that you don't have string algae? No stream or waterfall with string algae?
You raise a very good question. I'd say about 99% of people on the internet say reduced light and/or nutrients will clear green water. Millions of web pages say it.
Since you're thinking of going to the expense of building a cover to clear green water I think it might be worth while to look at this universal advice a bit closer.
Out of those millions of web pages giving the reduced light/nutrients advice I don't think there is a single page that shows anyone ever testing the theory. Even poorly conducted tests. And the test would be super cheap and easy. Kind of odd.
I'm going to take another wild guess that when you test the levels of ammonia and nitrate in your pond they will be zero. How do I know this? Your pond is green. Your pond is already full of plants sucking up nutrients as fast as they can be produced. Ammonia and nitrate are the two primary nutrients plants are suppose to remove to the point of complete algae collapse. Well, most people think it's only nitrate, but ammonia is actually consumed directly by algae.
There are five pretty big flaws to the plant theory.
1. The primary nutrient level is already zero and the algae is doing great. Adding more plants cannot drive nutrient levels below zero.
2. The concept that any kind of plant can consume all nutrients so another plants species will be starved into complete extinction is not based in any kind of reality. I don't know of any plant on earth that can do this. When you plant different plants together in the garden one isn't going to starve another to death. Each will use whatever nutrients comes their way. All will live just fine. Yes, the growth of each may be reduced by fewer available nutrients, but not enough to notice. They still grow just fine.
3. Single cell algae is first in line at the dinner table. When ammonia comes out of a fish's gills in a green pond that ammonia molecule has to somehow make its way past millions of algae cells that would love to eat it, and make its way to some plant or bacteria so it can be consumed there instead. Algae is not going to be polite and refuse to eat so some other plant can have dinner instead. Yes, some ammonia molecules will make it to the magic plants...but algae will get none??? Forgetting science this doesn't even pass a common sense test.
4. If nutrient level is zero in a green pond what is it when it clears? Well above zero. Exactly opposite to the plant theory. Dead decaying algae release nutrients back into the water and they also stop consuming nutrients produced by the fish so nutrient levels increase. Sometimes the ammonia level can climb so fast that fish can die from clearing a green pond.
5. Algae use these nutrients mainly to reproduce. Even if all nutrients could be completely removed the algae would not suddenly all die. They just couldn't reproduce. The pond would remain green for a long time.
Yes, algae needs sunlight. But apparently the internet thinks it requires full direct sunlight to grow. With any shade it can't grow and completely dies...while other plants do just fine???
OK, let's test that theory. Luckily there's lots of data we can easily check.
Go into any aquarium forum and search "algae". You will find tons and tons of people who have algae problems. These are tanks inside a house, in basements, normally away from windows. Some do have lights, but many don't. The amount of sunlight inside a house is very, very low. Much lower than even under a covered porch. Even aquariums with lights produce very little useable light. Yet algae problems remain wide spread.
Lets bump it up a little more. Google "swimming pool uncover green water". People in cold climates cover their swimming pools in the fall with pretty heavy covers and then uncover them in the spring. About 7 to 8 months of being completely covered. Really cold water. Pool water isn't know for lots of nutrients. Yet in the spring many people uncover their pools and spas to find bright green water. Not always, but often. Swimming pool forums are full of such reports. I don't know of a better test that shows how little light algae needs. It proves the theory that shade can clear a green pond is false imo.
Reasons for the myths.
The reason we have such myths is because if a person adds plants to clear a pond and the pond does in fact clear there is an assumption that it was the person's brilliance of knowing to add plants and that the plants did in fact clear the pond because they sucked up all the nutrients. No further testing is needed. But if they did do a couple of very simple tests the entire theory, or fact as many believe, would fly right out the window.
If you do build a shade structure be prepared to be disappointed. Now, ponds do just suddenly clear. And if your pond happens to clear sometime after you build the shade I assume you will consider your shade structure to be the reason. That's the human mind.
Why ponds clear in direct sunlight and water with plenty of nutrients and no UV.
A guy by the name of Norm Meck made an interesting discovery many years ago which he published in Green Water: Myths, Facts, Theories II. He found that if you poured water from a naturally cleared pond into water from a green pond that the algae would be killed on contact. Water in a naturally cleared pond is toxic to single cell algae. His theory was this toxic substance was produced by bacteria. That's a theory. That the water contains some toxic substance is not a theory.
It is well known that it's very common for plants to produce chemicals as a defense. Poisonous if eaten, chemicals that cause a rash if the plant is touched, etc. Most people know of such things. Less well known by most people, but well known in botany, is allelopathy. That's where plants produce chemicals that affect other plants in a positive or negative way. Super common in the plant world.
Algae in the sea have been found to produce chemicals that kill other species of algae. Unfortunately freshwater algae haven't been studied for this as far as I know.
There have been some recent experiments by a few aquarium keepers that seem to show (at least to them and me) that macro algae (any large multi-cell algae) do produce a chemical in the water that kills single cell algae.
Experiments I've done showed me that single cell algae may also produce a chemical somewhat toxic to macro algae. Also did experiments of adding a little bit of string algae to a green pond and had the pond clear over night. Didn't work every time, some times the string algae died instead. But pretty startling to see a green pond clear in the morning. Gets this person thinking.
Then there's a fair amount of anecdotal evidence. People often report in forum adding plants to a pond and the pond clearing. The assumption is the plants sucked up all the nutrients and the algae all died. But of course testing nutrient level disproves this theory. It occurs to me that when someone adds a pond plant that they are not just adding a pond plant. They're also adding whatever is on that plant. Fish eggs, insects, parasites, bacteria, virus and almost certainly algae. Good old macro algae, often called string algae. The scourge of many ponds. Because the algae is fairly protected by the plant and high up so it can get plenty of sun there's every chance the string algae can get a foot hold, start producing a chemical toxic to green water algae and clear the pond. Not every time of course, it's a battle.
I've read so many posts that say "I had green water but cleared it by adding plants...but now I have string algae" that it reinforces my belief that toxic substance is produced by string algae.
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