Bright UV light vs black UV lights for algea treatment

[snailaquarium]

Hi,

I read you can buy uv filters that kill algae, my brother has a black light, like the type you see in nightclubs, do these also kill algae or are they a totally different frequency? Only asking because of a big algae bloom in the pond! I'm going to do some water changing over the coming days.Thanks in advance.

 

[Colin_T]

Black lights are a type of Ultra Violet (UV) light.

If your brother has a black light in his room, he should not use it because it can cause skin cancer and cataracts. Black lights should not be sold to anyone because they are dangerous.

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UV sterilisers will kill singe celled algae that is floating around the water. But it won't affect filamentous algae or algae on rocks and the side of the pond.

A UV steriliser is basically a clear tube with a UV light on the clear tube. This is then covered by a case to stop the UV light getting out. Water is passed through the clear tube and the UV light kills things in the water. You need a slow flow rate of water otherwise the UV light doesn't get enough time to kill the algae or disease organisms in the water.

UV sterilisers are fitted inline after the filter, so the filter has removed the gunk from the water.

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Green water caused by algal blooms occur because of high nutrients and lots of light. They regularly occur in spring because nutrients build up in ponds over winter and then you get heaps of sunlight in spring and algal bloom.

The easiest way to treat it is with big water changes and sucking the gunk out of the bottom of the pond. Having floating plants will use the nutrients and reduce the light getting into the water. These plants can be removed afterwards and used as mulch on the garden.

 

[snailaquarium]

Black lights are a type of Ultra Violet (UV) light.

If your brother has a black light in his room, he should not use it because it can cause skin cancer and cataracts. Black lights should not be sold to anyone because they are dangerous.

----------------------
UV sterilisers will kill singe celled algae that is floating around the water. But it won't affect filamentous algae or algae on rocks and the side of the pond.

A UV steriliser is basically a clear tube with a UV light on the clear tube. This is then covered by a case to stop the UV light getting out. Water is passed through the clear tube and the UV light kills things in the water. You need a slow flow rate of water otherwise the UV light doesn't get enough time to kill the algae or disease organisms in the water.

UV sterilisers are fitted inline after the filter, so the filter has removed the gunk from the water.

----------------------
Green water caused by algal blooms occur because of high nutrients and lots of light. They regularly occur in spring because nutrients build up in ponds over winter and then you get heaps of sunlight in spring and algal bloom.

The easiest way to treat it is with big water changes and sucking the gunk out of the bottom of the pond. Having floating plants will use the nutrients and reduce the light getting into the water. These plants can be removed afterwards and used as mulch on the garden.

Thanks for the response Colin however it doesn't actually answer the query, can the black light kill the algae bloom or is it only the brighter types that can do that?

 

[Colin_T]

All UV light can kill algae.

 

[snailaquarium]

All UV light can kill algae.

Thanks, but yes def doing water changes. doing about ten watering cans a day.

 

[Byron]

The UV can kill most anything else too, just so you know. You may (or may not) deal with the algae, but bacteria (good and bad), organisms, fish will all be harmed if they are "hit" with the UV.

 

[Colin_T]

If you're going to do water changes to dilute it, do huge water changes (75-80%). It will dilute things better than small water changes.
Make sure any new water is free of chlorine/ chloramine before it's added to the pond.

 

[PheonixKingZ]

No black UV light!!!!!!!

I’m sorry for sounding harsh, but @Colin_T is right. Black UV light can cause skin cancer.

75%-80% water change will dilute the water a lot better than a smaller (aka 20%-30% water change).

 

[PheonixKingZ]

Sorry @Colin_T, that is pretty much exactly what you said!

 

[snailaquarium]

Surprised black uv lights can cause skin cancer, they were in many night clubs, I've done two small water changes so far will try a big one tomorrow. I read you need to have plants in the pond to help.

 

[seangee]

A UV steriliser is basically a clear tube with a UV light on the clear tube. This is then covered by a case to stop the UV light getting out. Water is passed through the clear tube and the UV light kills things in the water. You need a slow flow rate of water otherwise the UV light doesn't get enough time to kill the algae or disease organisms in the water.

Thanks for the response Colin however it doesn't actually answer the query, can the black light kill the algae bloom or is it only the brighter types that can do that?

I think it does. The black UV light won't kill the algae if you just shine it over / into the pond, but may cause other issues. The UV filter as Colin described will work. But they are pretty cheap so he may as well just buy one. Also the bulbs have to be changed regularly. They are actually only good for about 6 months of continuous use. The manufacturers say replace annually because you won't have algae in winter. So chances are his bulb / tube won't work anyway even if placed inside an appropriate filter.

UV sterilisers are fitted inline after the filter, so the filter has removed the gunk from the water.

@Colin_T good way to start an argument on a pond forum . The alternative view is fit before the filter so the filter catches what it kills. My bets are hedged as I have 2 filters in series with the UV filter between them.

 

[seangee]

If he already has a filter and pump this is the type of thing he needs https://www.allpondsolutions.co.uk/11w/

He will need to check what the appropriate wattage is for his pond size and the flow rate of his pump. The flow rate is really important. They do work. The standard advice to control the causes of algae (light and nutrients) are a lot harder for an outdoor pond. My pond is pretty small (for a pond) at 7000 litres. Water is metered where I live so water changes are expensive and not that easy to do. I certainly don't do weekly changes like in my tanks. As for light - right now my pond is getting around 18 hours of sunlight in a day so without the UV I wouldn't be able to see my fish.

Plants do help, so does the algae that grows on the pond sides and rocks - but without UV you are likely to spend most of your sppring and summer fighting algae blooms. With it your water should stay clear all year.

 

[snailaquarium]

Well it's not usually this bad.

 

[snailaquarium]

Would any particular algea eating fish control it or is that naive thinking?

 

[Byron]

Would any particular algea eating fish control it or is that naive thinking?

No where in this thread is the algae species identified.

Problem algae is usually (if not always) well beyond the capability of fish to handle, and the fish (if they exist) have their own requirements/needs that must be provided. Some fish that are especially good at eating "algae" usually have very specialized diets. There are many species of algae, and as an example, in an aquarium otos are very ravenous when it comes to diatoms or common green algae but they will not touch "problem" algae like BBA, etc.

That is in general. Here the initial issue was in a pond. Goldfish are commonly kept in ponds and they are certainly vegetarian. But I do not know if they have any value in eating "problem" algae. But it is never a good idea to acquire any fish solely to deal with a "problem" whatever it may be, as this often results in even more problems.