Garden pond keeps turning green!!!!

[no1special]

I put a small pond (approx 5'x4'x2' deep) in my garden about 4 weeks ago and have a fountain and waterfall running off one pump.
For the first couple of days the water was lovely and clear. However, after a week or so, I couldnt even see the pump as the water was so green! i emptied the pond, gave the sides scrub, and re-filled with clean water. A week later and its green again!! I tried using this stuff http://www.petstuffonline.co.uk/aquatic-products/r... but it didnt make any difference.
The pond is in constant sunlight, and I am aware that the sun will cause algae to grow. Is there anything else I can do, or add to the water to stop so much algae from forming, or should I just empty the pond once a week to keep the water clean and fresh?
Incidentally, the pump has no sponge filter in it, like my Dads one used to have many years ago....would a sponge filter make any difference?
Thanks all

[daveparry]

Algae forms from nitrogen and sunlight, you need to have nitrogen loving plants in there to compete with the algae, good luck! or buy a filter system that incorporates a UV light.

[no1special]

daveparry said:

Algae forms from nitrogen and sunlight, you need to have nitrogen loving plants in there to compete with the algae, good luck! or buy a filter system that incorporates a UV light.

Thanks Dave. Someone else mentioned a UV light, so might give that a go, along with the nitrogen lovers!

Cheers

[AcidReflux]

We had the same problem in our pond at the beginning of this season. A combined Hozelock filter/UV light fixed the problem within a month. The UV light makes the green algae clump together (apparently) and the filter traps the clumps. The filter will also encourage bacterial growth within the water which will have a beneficial effect on your pond's overall natural balance.

We bought this but RRP is over £100 so it's an expensive solution and it lives above the ground:
http://www.hozelock.com/aquatics/pump-and-filter-k...

I read good things about these all-in-one things that replace your existing pump, for about £70:
http://www.hozelock.com/aquatics/pump-and-filter-k...

If you want to encourage wildlife into your pond then replacing the water every week with fresh tap water will be disasterous. You might as well pour bleach into it to stop the algae growing.

Edited by AcidReflux on Tuesday 20th July 08:46

[no1special]

AcidReflux said:

We had the same problem in our pond at the beginning of this season. A combined Hozelock filter/UV light fixed the problem within a month. The UV light makes the green algae clump together (apparently) and the filter traps the clumps. The filter will also encourage bacterial growth within the water which will have a beneficial effect on your pond's overall natural balance.

We bought this but RRP is over £100 so it's an expensive solution and it lives above the ground:
http://www.hozelock.com/aquatics/pump-and-filter-k...

I read good things about these all-in-one things that replace your existing pump, for about £70:
http://www.hozelock.com/aquatics/pump-and-filter-k...

Edited by AcidReflux on Tuesday 20th July 08:46

Thanks Acidreflux, I think I'll give your one a go.

AcidReflux said:

If you want to encourage wildlife into your pond then replacing the water every week with fresh tap water will be disasterous. You might as well pour bleach into it to stop the algae growing.

Good point, thanks for making it!! Already have a couple of frogs that like to swim and knock about round the waterfall, so I'll refrain from changing the water!!
Thanks again
N1S

[MrV]

I would go the UV light route something like this is more than adequate for your pond


http://cgi.ebay.co.uk/Pond-UV-Light-Sterilizer-Aqu...

[daved]

Same thing here. Pond water had clouds of green stuff floating around after a couple of weeks. We bought what I think are barley pellets in a net bag and dropped it in. Green stuff started to go brown immediately but it was a few weeks before it started to disappear. All gone now but that might be down to the lack of sun and not because of the barley stuff.

[no1special]

MrV said:

I would go the UV light route something like this is more than adequate for your pond


http://cgi.ebay.co.uk/Pond-UV-Light-Sterilizer-Aqu...

Thanks MrV, just bought this one from Ebay. The above-ground one was a bit too bulky so hopefully this will do the trick!
I'll report back here once it arrives and has been fitted!
Cheers

[AcidReflux]

no1special said:

MrV said:

I would go the UV light route something like this is more than adequate for your pond


http://cgi.ebay.co.uk/Pond-UV-Light-Sterilizer-Aqu...

Thanks MrV, just bought this one from Ebay. The above-ground one was a bit too bulky so hopefully this will do the trick!
I'll report back here once it arrives and has been fitted!
Cheers

I'm no expert, but MrV: how does this UV-only device clarify the water? It seems like it will clump the algae but without a filter to collect the clumps, how will this clear the clumps from the water? The OP doesn't have a filter at the moment. Does a UV light on its own clear green algae?

[Simpo Two]

Glyphosate has (or did have) clearance for use as an aquatic weedkiller, ina very low dose.

However if you want other plants in there it might kill those too.

[drive2tractors]

Chlorine?

[spikeyhead]

you'll need a filterbox at the top of the waterfall to get any benefit from the UV light.

[The real Apache]

We use a boggo pump with UV lamp, works a treat

http://www.ketteringkoi.com/

[58warren]

Ponds will always go green when newly built and freshly filled with tap water. As mentioned, oxygenating plants will help, but the UV filter will really help (it will need cleaning periodically to keep it effective). Plants that shade the surface will help as they reduce sunlight into the water and provide cooler conditions for fish to shelter.

Don't keep replacing the water as any pond life will suffer and the water will contain chlorine, which isn't great for aquatic life.

Ponds will settle down with time, but the recent hot, sunny weather will exacerbate algae/blanketweed/duckweed even in an established pool. The rivers around the Olympic Park are bright green with a proliferation of duckweed at the moment!

[otolith]

UV clarifier without a filter will prevent algal blooms by killing suspended algae before they become a problem. It will also tend to clump the algae, so that if you had a filter with decent solids removal, you could clear an existing bloom fairly quickly. Otherwise, you will have to wait for the dead algae to sink and decompose, which could take some time.

UV clarifiers are great - but once you clear the water column of suspended algae and let the light get to the bottom, your battle with filamentous algae (blanket weed) is about to start.

A few points -

• Algal blooms are natural, and most shallow water bodies will undergo them at some times of year. They can be prevented, but don't forget that you are trying to create and maintain an unnatural situation, so it will take a little effort or design to do so.

• If you want to avoid or minimise them, you will need to deprive the algae of fertiliser or light or both. This is best achieved by using fast growing plants which will out-compete them. We used to use a shallow pond filled with watercress and reeds to do this, which received the water from the filter on its way back to the pond. Watercress soaks up nitrate and phosphate very effectively, grows like a weed and gives you salad and compost heap filler. When you are removing armfuls of watercress, you are permanently removing fertiliser from the system.

• To deprive the algae of light, use plants with floating leaves - you'll need to cover a fair proportion of the surface to have any effect

• If you have fish, most of the fertiliser going into the pond will be coming via them, from the food you give them. Lower density of fish => less or no artificial feeding => smaller nutrient flux. The more fish you have and the greater the amount of feeding, the more effort you will have to make to take those nutrients back out of the system. Fish will also tend to grub about in the sediments. This has two effects - it makes the water murky, and by exposing the sediment to oxygen it releases phosphate bound to it into the water column, where it is available to algae.

[netherfield]

Gardeners world reckon a net bag of barley straw sunk in the pond will help,iirc a brick was used to help it sink.

[otolith]

The evidence for the efficacy of barley straw is mixed. Probably won't do any harm, though.

[AMLK]

I would second the use of barley straw. One bag of it will keep your pond clear for several months. Cheap, easy and natural.

[dirkgently]

Buy or build a bio-filter (Google is you friend) forget about UV filters, install and wait. After six weeks or so the Algae will disappear as the pond finds a balance, patience is needed as natural processes need time to sort themselves out.

[otolith]

A biofilter won't prevent green water - it's just there for the benefit of the fish to facilitate the completion of the nitrogen cycle - ammonia to nitrite to nitrate. Algae can use all three forms as a nitrogen source, so it makes no odds to them.