UV Lights

I've decided to clean out my pond and am looking to stop the water going green again.

The current pump (Pontec) does not have a filter or uv light.

I've seen a Pontec pump with a built in filter but no UV light - given the my pond is only 4m2 - is a UV light really necessary - and what does it do anyway - is it a gimic?

ta

 

Hi,

No, UV is not a gimmick and if mishandled can be harmful to your eyes and skin , so do not test it out looking directly at the bulb.

It may help with green water but its a kill all type of device, knocking out what you don't want but also all the other microbes etc that could be beneficial.

How old is you pond ? they say you should remove all the sludge at the bottom of the pond, but unless very thick I used to leave it, again probably more good stuff in there than bad.

Usually a pond will clear up in the second or third year but it also depends on the volume of fish and plants you have in there, most folk overfeed the fish, hence high nitrates and green water.

Today there are some very good biological green water products that are quiet selective and safe in their action.

Think I would look at just tidying up the plants, use a good green water product and reduce any feeding to just once a week if you have normal goldfish, even they can kid you on they want more food !

 

Have a look at all pond solutions on the net quite cheap and good service I got a pressurised filter with built in uv light and it keeps my pond lovely

 

I would consider improving the amount of shading on the pond surface first.

Planting shrubs by the pond to create shadows cools the surface temp reducing green water as would growing water lillies.

Works for me. Pond is shaded by tree in morning and by bamboos in afternoon. Some sun hits pond which keeps the fish happy.

I was told my fish would need filters etc etc to survive but 20 years on they are happy and now number 60 odd

 

UV works by mutating the algae particles, causing them to clump together. This in itself doesn’t kill the algae. As water passes through the filter, the algae particles are normally too small to be caught, but because they have been clumped together and therefore made larger, they can be filtered out. Very effective.

 

Yep and when you clean the filter be prepared for a stink I thought comfrey tea was bad

 

So it sounds like its worth shelling out for the UV light .

Some good advice - thanks everyone - I was wondering why bother with a UV light if you have a filter - u've answered that question Freddy.

It's true what they say - you learn something new every day .

 

If the filter is cleaned regularly, this shouldn’t be an issue.

 

I did - they are also on ebay .

Their 'own' brand all in one pump, uv and filter appears to offer best value - so just placed an order.

Cleaned out and refilled the pond today - so hopefully this pump will keep it clean.

 

Happy days glad I could be of help

 

I've never used a UV light on my pond, it tends to go green each year, but once the balance gets right it clears, then there is no problem for the rest of the summer.

One thing that does bother me regarding UV lights if you have fish is that the green water indicates an excess of nutrient in the water, which might be harmful to fish, the algae are living on that nutrient.
So I just wonder if totally clear water, due to a UV, might be misleading regarding water quality.

 

I wouldn’t say that clear water is indicative of water quality. Totally clear water can be toxic to fish, ammonia and nitrite spring to mind. I’m a bit sceptical about this excess nutrient thing when it comes to algae. With my last (Koi) pond, I filled it with water, just before I went away on holiday for a week. When I came back, it was pea soup, no fish, no feed, nothing.

 

Any water left to stand in sunlight will go green, not sure how the nitrogen gets in there, but it does.
Uncovered water butts come to mind.

I know it is the other end of the scale, but water under a covering of duckweed is always clear, presumably because the light is excluded.
But the duckweed must be living on something.

 

One further question if I may.

Does anyone have underwater lighting?

I directed a garden flood light to the top of the pond the other night - and the effect was quite spectacular - that rippling light effect you see by swimming pools. I'm just wondering whether underwater lighting would be just as effective?