Cannot get rid of green algae


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Hi
1000 gallon pond, steep sides, no plants, 5 Koi, all test readings low except for PH (8.5). The pond is about 15 years old. In the last five years I have failed to maintain a clear, algae-free pond for longer than a couple of weeks. Oasis green2clean 24000 combined filter and UV (25watt) with an Oase Aquamax 8000 (litres per hour). I have tried a whole range of products and processes to try to clear the green but nothing lasts more than a week or so. I have completely replaced all the filter pads (I had an infestation of worms in the old set and wondered. Whether this was causing part of the problem). The garden is south facing and the pond gets direct sun for most of the day.

I have two questions...

Short term - can anyone suggest any products or processes that might clear my pond?

Long term - Next year I am looking to redesign the water feature and could change the filtration system for a new one at the same time. Recommendations, please, for what I should consider purchasing? I live in South Wales, UK.

Many thanks

Chris
 

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The answer is in your first sentence - 1000 gallons, 5 koi, no plants. Your system is overloaded because your fish have outgrown your pond. You can try: 1. less fish 2, more filtration 3. add plants. (2 & 3 are really connected, but while you could add other biological filtration, nothing has the ability to scale itself up to your situation like nature.)

But honestly, your fish will continue to grow and this will be an ongoing problem unless you find a permanent solution - which means fewer fish or bigger pond. All the chemicals in the world won't "fix" the problem because Nature knows what the real problem is - your pond has too much excess nutrient load. That green water Is saving your fish, so I'd suggest you want to stop fighting it until you resolve what's causing it. Just attacking the algae is like treating a fever that's caused by an infection - you can bring the fever down, but unless you resolve what's causing it, you'll end up dying from the infection. Same for your pond - unless you resolve the issue, your fish will end up sick or worse.
 

Jhn

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There are no products/chemicals that are anything other than a bandaid at best, and at worst detrimental to your ponds overall health.

The worms and all day sun aren’t the problem, problem is too many large messy fish in an inadequately sized pond, which drives the nutrient load up. Without any plants in the pond there is nothing to consume those excess nutrients other than the free floating algae/green water.It is going to be next to impossible with out using plants or purchasing a vastly oversized filter system to drive the nutrient load down in the pond to prevent the green water as it is now.

Green water other than being unpleasant to look at, is actually helping maintain the water quality in your pond.

If it were me I would either rehome the koi and go with goldfish or if you plan to enlarge the pond next year to say At least 5-6000 gallons, I would try to maintain the water quality in the pond putting up with the green water for this season. Then when you redo the pond make it larger and add a bog or wetland filter onto the pond....minimal maintenance and more time for you to sit and enjoy it.
 
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I should have added WELCOME to the GPF! We're happy you're here! You've come to the right place as there are lots of helpful, friendly ponders here!
 
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@Jhn and I were typing at the same time - so you'll see that the advice you're getting is something that we share ALL THE TIME. Your problem is not unique - lots and lots of ponders find themselves in the same situation as their fish outgrow their pond. I really wish people who sell koi would be more responsible about where they send those fish to live - 1000 gallon ponds are great goldfish ponds, terrible koi ponds.
 
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Thank you both very much for the prompt, no-nonsense, helpful advice. I clearly have some rethinking to do about the design of my pond. One of the challenges I have in enlarging the pond is that I originally built it backwards. That is to say, there was a larger tank area that I reduced with simple formwork and concrete. Enlarging the pond will mean removing all the fish and breaking up a large amount of concrete. Would placing a second filter and UV into the system be adequate for the size of pond? Or would this, again, just be adding sticking plaster?
 
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And thank you for the welcome... I think this may be an essential forum to my future ponding success!
 
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You need lots of plants to compete with the algae. Remember, algae are plants too.
The more plants, the better.

There are floating plants as well that don't require planting. Just toss them in. However, your koi will most likely devour their hanging roots. You can protect their roots by placing them in floating mesh planters.

If your home's water is chlorinated, don't rinse your filter pads with that. The chlorine will kill the good bacteria.
 

sissy

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Welcome and yes koi get big and no one warned me and now wish I had been on this forum back then .Over 5000 gallos and still not enough .I do use koi clay to bind the algae and kill it and send it to the filter but plants and plenty of aeration are needed also
 
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addy1

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Welcome to our forum, agree with all the above.
I have shubunkins did not want koi for the reasons stated above they get huge, require a good amount of water and filtration.
 
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Thanks to everyone for the advice. Currently thinking about increasing the size of the pond. One of the Koi, (named Comet) is probably about 25 years old and I would be sad to part with him. I am a little concerned that the shock of transferring him to a large tank while I enlarge the pond might prove too much for him. Any advice on whether this would be wise?
 
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@Denhamcs also consider building a bog filter with or without your filter. Bog filters will clean pond water and feed plants you place within it without the need of using filters and also cleaning them.

It's all natural cleaning process but does depend on your bioload. Many of our friends over the pond in here use bog filters and nothing else with great success.

Have a gander on this one. Just think, one electrical socket for the pond pump to bog and back down your waterfall, that's it :)
 
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Thanks to everyone for the advice. Currently thinking about increasing the size of the pond. One of the Koi, (named Comet) is probably about 25 years old and I would be sad to part with him. I am a little concerned that the shock of transferring him to a large tank while I enlarge the pond might prove too much for him. Any advice on whether this would be wise?
Mixed results on moving the koi. There are people here that take their fish inside every winter with no problems.
I was in your situation at one time and lost a rather large koi. To me it seems stressful to chase them around with a net. I had one hop out of the temporary container and even though I retrieved him immediately, he didn't survive. I guess it was too much of a shock for him jumping out and landing on the ground.

So, I don't know....mixed results, as I said.
 
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Many years ago (decades) the Fort Worth Zoo had an aquarium inside the grounds, and immediately adjacent to the entrance door, on both sides, were two small pools of large koi - small as in 2-3 feet deep and perhaps 2-3 feet wide and 10-12 feet long (rectangular). And they were brim FULL of fish. Jammed with fish! No plants, just crystal-clear, flowing water that must have run through a filter the size of the Space Shuttle...
 
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Many years ago (decades) the Fort Worth Zoo had an aquarium inside the grounds, and immediately adjacent to the entrance door, on both sides, were two small pools of large koi - small as in 2-3 feet deep and perhaps 2-3 feet wide and 10-12 feet long (rectangular). And they were brim FULL of fish. Jammed with fish! No plants, just crystal-clear, flowing water that must have run through a filter the size of the Space Shuttle...
We visited a public garden that had an indoor growing space with a "stream" running through it. Less than a foot deep and teeming with big koi. It was really beautiful and well done, with a number of small waterfalls and pooling areas, but I was worried about the big fish. We asked and they said the filtration was massive and the volume of water was much larger than we guessed. They also said they used the water from the fish to water the plants in the arboretum - and they were lush and beautiful!
 

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