Pond water green algae

[tharriso]

Hey ph I have 5000l pond with small goldfish koi etc.
The water is not very clear at all green.
The filter has a 11w uv clarifier in it.

Last week I added a massive 72w uv clarifier. It has made no difference at all.

I have used those green water treatments they are fantastic but return to normal within a week.

Any pond experts got advice for this?

[TallPaul]

Too exposed, not enough shade and getting too much sunlight?

[RichB]

What type of filter do you have?

[wolfracesonic]

I've got a 55w on my 10000l set up, which keeps the green stuff at bay and is rated for 25000l. As above, what type of filter do you have? The UV doesn't remove algae, it kills it so it clumps together so it's big enough for the filters to pick up: 'flocculate' is the posh word. I'm also about to put my shade sail up which keeps a lot of sunlight of the pond.

[tharriso]

Thanks

No more than half of the pond is in sunlight at midday. A third is covered with lily pads.

The filter says oase 6000, so assume that's meant for 6000l?

The pump is 65l/h 55w.

[roofer]

Oxygenation is the key.

[yellowtang]

Are the UV bulbs new or no more than 6 months old? - they are only useful for 6 months really.

Have you cleaned the Quartz sleeve surrounding the UV bulb? - if this isn't really clean, the UV cannot get through.

Is the pond overstocked with fish? - too many fish and or over feeding will push the nitrate and phosphate levels up. When this happens, combined with warm sunny weather, the pond will be green/cloudy regardless. Do not overstock/feed!

What type of filter do you have? Is running all day, every day? ( sorry to ask, but you'd be amazed at how many people turn them off! )

Do you have filter floss in the filter box? - this is needed to remove all the suspended dead algae cells.

Do you have a carbon mat in the filter box? - this will help remove excessive nutrients.

Do you have a good flow from the filter? Water flow helps to oxygenate and this will help in clearing the water.

[ViperDave]

The Algae needs nutrients to grow, therefore to stop it growing you need to export nutrients from your pond, in a fish tank this is usually done by water changes, in a pond its not so practical, you can export nutrients with plants using them up and out competing the algae, watercress is a good plant to do this if you have the right setting, alternatively you can filter out the algae itself, you can use a UV to kill it and get it to clump together so it is mechanically trapped in your filter, but you then need to do some work, you need to get it out of the filter, otherwise it will just decompose and return all the nutrients back to the water ready to feed new algae and all the time this is going on your fish are still eating and putting more nutrients into the water.

So if you want an easy life that isn't continuously cleaning filters and fighting green water, you need so good fast growing plants that use up those nutrients and are easy to prune and throw away thus removing nutrients from the pond system.

[Chris Jay]

Barley straw is very good at keeping algae down until the pond establishes it's own eco system.

I found the water treatments to be a waste of money, much better to add oxygenating marginal plants.

Edited by Chris Jay on Sunday 28th June 08:32

[spikeyhead]

tharriso said:

Thanks

No more than half of the pond is in sunlight at midday. A third is covered with lily pads.

The filter says oase 6000, so assume that's meant for 6000l?

The pump is 65l/h 55w.

That sounds a tiny pump for a pond of that size, unless it's set up with lots of plants and bugger all fish.

[anonymous-user]

more plants

out competing the algae is the best solution

[tharriso]

spikeyhead said:

That sounds a tiny pump for a pond of that size, unless it's set up with lots of plants and bugger all fish.

I was thinking that myself, I think it might mean 6,500L/H ? It is 55W so would have to be horribly inefficient to only push 65l/h. It was bought as a package with the filter. Definitely says 65l/h though.

Anyway I have just bought a 18,000l/h pump off ebay, see what happens.

[W12GT]

Firstly the UV doesn't kill the algae:- it changes its structure making it stick together which a mechanical filter then takes out. The mechanical filter needs cleaning regularly to prevent it becoming blocked - best to do in a bucket of pond water to prevent killing any good bacteria that may be on it.

Your pond also needs biological filtration which is what keeps it healthy - but not necessarily clear!

It is a common misconception that clear water is healthy water- not true - it is very common to have a very healthy pond that is murky - in fact the best koi from Japan are grown-on inud ponds!

The pump you have bought sounds too big; way too big. The aim is to turn the water volume over once every 1-2hours. So a 5000 litre pond needs a pump that will do 2500-5000 litres. You will also need to check the maximum flow rate of the UV and the filter itself.

Buy a test kit and see what is going on in your pond:- I believe the nitrate and nitrite levels will be quite high which isn't good.

Good luck!

Edited to add:-
Is it one of these?
http://mobile.oase-livingwater.com/en_GB/water-gar...

If so that is only suitable for ponds with fish up to 3000litres. To be honest even that is way too optimistic. Flow rate isn't specified but will be around 1000litres per hour.

Edited by W12GT on Sunday 28th June 12:24

[tharriso]

W12GT said:

The mechanical filter needs cleaning regularly to prevent it becoming blocked

Not sure when this was last done might do it tonight thank you.

W12GT said:

The pump you have bought sounds too big; way too big. The aim is to turn the water volume over once every 1-2hours. So a 5000 litre pond needs a pump that will do 2500-5000 litres. You will also need to check the maximum flow rate of the UV and the filter itself.

Can the water be over-filtered? Is it a problem? It has to pump about 2m high so I thought you need more power to do that?

W12GT said:

Buy a test kit and see what is going on in your pond:- I believe the nitrate and nitrite levels will be quite high which isn't good.

I testing every two weeks lately and the levels are always good I think the water is good but murky.

W12GT said:

Is it one of these?
http://mobile.oase-livingwater.com/en_GB/water-gar...

That sort yes not sure if that exact model but looks the same yes.

[myvision]

Are you sure the UV is on I run a 55w on 12,000 litres without an issue.

[drivin_me_nuts]

I have a problem similar to this. I have a 5000 litre pond with no fish and at the moment it is plagued with string algae. Ii half emptied the pond a few weeks ago and added back fine clay that seems to have clarified the water, as well as a sludge eating bacterial treatment. It's all good and the water is Crystal clear , or it was, but note the algae is back. so now I'm thinking about plants. the pond has been established ober 12 years and has plenty of plant life, which I suspect is part of the problem 're. decomposition. Can anyone please suggest some oxygenating shallow water plants that might help.

thanks.

[myvision]

String algae? I presume you mean blanket weed I use this for it.
http://www.amazon.co.uk/Cloverleaf-Blanket-Answer-...

[IanA2]

Chris Jay said:

Barley straw is very good at keeping algae down until the pond establishes it's own eco system.

I found the water treatments to be a waste of money, much better to add oxygenating marginal plants.

Edited by Chris Jay on Sunday 28th June 08:32

Yup, I put in a large pond about ten years ago. For the first couple of years it was all algae. I was dubious about barley straw but tried it and it worked. Been clear as a bell for several year now though it took some months to settle down. See: http://www.ceh.ac.uk/sci_programmes/documents/barl...

[RichB]

tharriso said:

W12GT said:

Is it one of these?
http://mobile.oase-livingwater.com/en_GB/water-gar...

That sort yes not sure if that exact model but looks the same yes.

That's what known as a canister filter/pressurised filter and generally they are now considered as good as the open gravity filters however because you can bury them that are popular. I have a 6,500 ltr pond with koi, goldfish, tench and orfe and MrsB more or less insisted on a canister filter that could be hidden. For 6,500 ltrs I bought the Oase 30,000 filter on the basis that you should double the number if the pond is in sun and double it again if it has koi. And, even with that size filter I struggle with murky water. The other problem I have is that I can't have oxygenators or much plant life because the koi just eat it. They will polish off 25 quids worth of elodia in a few days, and that's an expensive salad bar! IF you don't have koi I would chuck in tons of elodia and hornwort.

[W12GT]

RichB said:

tharriso said:

W12GT said:

Is it one of these?
http://mobile.oase-livingwater.com/en_GB/water-gar...

That sort yes not sure if that exact model but looks the same yes.

That's what known as a canister filter/pressurised filter and generally they are now considered as good as the open gravity filters however because you can bury them that are popular. I have a 6,500 ltr pond with koi, goldfish, tench and orfe and MrsB more or less insisted on a canister filter that could be hidden. For 6,500 ltrs I bought the Oase 30,000 filter on the basis that you should double the number if the pond is in sun and double it again if it has koi. And, even with that size filter I struggle with murky water. The other problem I have is that I can't have oxygenators or much plant life because the koi just eat it. They will polish off 25 quids worth of elodia in a few days, and that's an expensive salad bar! IF you don't have koi I would chuck in tons of elodia and hornwort.

It can never match a gravity fed system because you still have a pump or suction hose in the pond. The only true way to have a debris free pond with minimal maintenance is to have a bottom drain. The debris and waste doesn't all get mashed up by the pump so it is filtered out easily with a mechanical filter such as a sieve or vortex or brushes etc. I'm currently using a sieve and it is so easy to maintain but I'm still not convinced it is better than a couple of large vortexes that I have previously used!