Koi Keeping.....


Recently a couple of members within the space of one week told me about their new winter covers and they were quickly “volunteered” to produce some pictures and details of their covers.  If you have a good idea for a cover for winter please let us know as the cost of fuel is so high that anything that can keep temperatures up over winter is a great asset.  A few pictures and a few words is all that we ask.  Incidentally when discussing our energy cost with EDF they told me about a new tariff called Eco 20 which is not dissimilar to the old white meter.  It means that energy consumed at night time and all weekend is charged at a considerably lower rate so those people with electric pond heaters should find it beneficial. Unlike the old white meter, there is not a penalty on the daytime rates so, at the time your electricity has been consumed the most during the night, you will pay less and the meter costs nothing to install.  Mine went in 27th November, I will let you know if it is worth it.  I have purchased a new alarm clock so that I can set it for 2am for Sue to turn the dishwasher on and 3am to turn the washer on!!!  Funnily enough she didn’t seem too keen when I told her of the plan.

A few phone calls produced more pond covers and thereby produced a superb article for the December 2009 newsletter.

Tony McCann
Chairman, Northern Koi Club


Trevor Fielding - There is no other way of describing this article other than a load of balls!
This afternoon I was phoned by Tony McCann Minor of the 4th Form at St Mary’s School Swinton. He was behind the bike shed, so that Sue couldn’t hear him and I could tell that he was sniggering like a typical schoolboy while he was asking me to write an article for the newsletter. The subject was, wait for it, my balls.

Perhaps I should apologise, at the outset, because this article, must, of necessity, contain many double entendres which might offend the more sensitive members of the club. I am well aware that this is exactly what Tony McCann Minor of the 4th Form, he of the salacious mind, is actually hoping for.

I was introduced to this topic by Geoff Morris whose balls I have admired from afar for some time. I was even more impressed when he told me that they were 50mm in diameter and when he dangled them in his pond they reduced the heat loss quite considerably. Perhaps surprisingly their sudden appearance did not worry his fish at all and they were quite happy to nibble on them. Geoff also told me that Chrissie washed his balls every spring because they had become covered in algae.

Perhaps I should go on to explain that  these balls are actually manufactured by a company named Weener Plastic Packaging Group. Website www.euro_matic.com    Whilst they manufacture balls of various sizes the ones that Geoff & Chrissie, and now myself, use are 50mm in diameter and they are made out of polypropylene. The company claim that they can reduce heating costs by up to 75%.

The technical details state that a thermal insulation barrier is achieved through the air in each ball and the poor heat conductivity of plastic. The air pockets between the balls also contributes to the cellular insulation system which also dramatically reduces heat loss. They still allow light through into the pond and this must obviously benefit your fish.

As far as I can recall I covered approximately 90% of the pond with the balls at the beginning of December and I left them there until the end of March. I had dropped the temperature to 55 degrees Fahrenheit (I still work in old money). Whilst it is impossible to calculate exactly what the savings are my gas bill was reduced quite considerably – although, to be fair, the last winter was more mild than usual.

Other advantages are that it is still possible to see your fish and check that they are OK. The koi can also be fed as they can nose through the balls to get at the pellets. There is also no maintenance apart from fishing them out of the pond. I must say that I didn’t bother washing them and I really don’t think that this will be a problem.

On the downside the balls are quite expensive although they will last for many years (hopefully).

When the Yorkshire Koi Society visited my pond earlier this year one delightful young lady asked if she could see my balls. I really thought that this must be my lucky day so I invited her to come down to my shed. But that’s another story. Nuff said!


Geoff & Chrissie Morris - Insulating a Koi pond with plastic balls

• Our pond is heated, with the thermostat set at 15 degrees C (59 degrees F)

• When working from home, I would watch the steam rising from the pond each morning, thinking, we’re paying for that steam!

A cover of some description was required, but what properties must it have?

• It must not blow away – our rear garden is very windy
• If it does blow away, it must not cause any damage
• It must not look too ugly
• It must pack away for the summer without needing a second garden to store it
• We must be able to feed the fish
• The fish must not be able to strand themselves by jumping on top of the cover

What we considered:

  • A cover like David and Audrey’s
    • We don’t have a pergola and if we constructed one it would shade our garden and our neighbours
  • A temporary frame to attach the cover.
    • It would need to be very strong to cover a pond 6 metres x 4 metres, irregular in shape on one side and built up on another. It would need to be securely anchored to the floor and would be in danger of blowing away
  • Floating swimming pool covers constructed from polystyrene slabs covered on PVC www.aquawarmswimmingpoolcover.co.uk/aquawarm-swimming-pool-covers-in-use.htm
    • The fish could possibly jump on top, and when I enquired about the PVC covers, was informed that PVC leaches chemicals. Different manufacturers and colours would leach different chemicals
  • Plastic balls – the type used in children’s play areas www.euro-matic.com
    • These plastic balls – not table tennis balls as some have suggested – are used to cover drinking water reservoirs near airports to discourage waterfowl, which apparently don’t mix too well with aircraft engines!
    • The balls can be purchased in various sizes, and with help from the distributors, we chose 50mm ones
    • They spread out on the pond surface and will spread into all the nooks and crannies of an irregular shaped pond, including the skimmers if you’re not careful
    • They cannot do any damage if they are blown out of the pond. It is very rare for them to get blown out, but when the fish bred, they threw out about one thousand balls in one day – naughty fish!
    • They are available in various colours but we went for clear, to allow light into the pond
    • For extra insulation, they can be stacked into multiple layers
    • The manufacturers claim:
  • Heating costs reduced by 75%
  • Evaporation reduced by 90%
  • Reduces penetration of Ultra Violet rays, precluding growth of algae and clogging weeds
  • The rate of ice formation is reduced in freezing conditions, lowering the ice formation point by up to 10°C (50°F)

Anything else, well they form nice geometric shapes on the pond surface after the wind has blown them about a bit.
The fish can still feed through them and appear to enjoy pushing the balls about.
I use some pieces of waste pipe to form a 1m x 1m area, without balls, for feeding.
They are easy to store, just put them back into the plastic bag and cardboard box they came in and store them in the loft.
The only downside is that they can get covered in algae on the bottom, we are thinking of adding salt to the pond this winter so we expect that to solve the algae problem.


John Shepherd

My cover is made from 2 layers of bubble wrap to make a type of double glazing.  The bubble wrap usually lasts 2 years and costs £40 for 50 metre roll and 1.5 metre wide.  The centre is a 20ft. long TV Arial mast with timber cut outs to take the tube.  The total cost was about £100 using 3 x 2 scant timber which is cheaper and takes about 4 or 5 hours to put it together at the start of each winter.  It is now 6 years old with a couple of bubble wrap replacements and has served me extremely well.


Chris Pyle
I’ve kept Koi for 17 years, 10 of those years I’ve heated my 5,500 gallon pond all the year round  and the people who know me will tell you that I swore blind that I would never cover my pond as this is a hobby that should be  appreciated all the year round  . This all changed when this time last year when after a cold spell we got are biggest gas bill ever. So I made the decision to cover the pond.

After much consideration and planning I finally came up with a design which would be constructed using polycarbonate sheets (5 walls) and 3x2 timber. The design would consist of a simple wooden frame which would bridge over the pond , but each section would hinged so that the whole construction would fold away  making storage a lot easier. For people who have seen my pond will know its pear shaped and partly edged with boulders. I over came this by bridging over the boulders and as well as walling around the boulders with poly carbonate sheets I filled the gaps with bubble wrap.
The middle section of the cover is hinged like a trap door to allow access. The gap is not big enough for me to get in with a net but it enables me to have a good view of the whole pond.

As well covering the pond we replaced our combi boiler with a new  balanced  flue boiler .Since making these changes our gas bills are 35-40% less than the previous quarter for that time of year.

As for the fish they’ve never looked so good through winter, as not only has it stopped sudden temperature drops, but it keeps the rain out and stops ph fluctuations.


David & Audrey Evans
With the building of Pond 3 in September 1998 – which has a 6kW Electric Heater – a pond cover for winter became a priority. We had seen polycarbonate covers with and without frames, and thought – how would they be held down and where would we put them when not in use?  While mulling this over, we were invited out one Saturday evening, by a then member of the Koi Club – an American lady [Laura ???] and her husband who lived in Rochdale. Alan and Ann Kershaw were also there that evening.

Their pond had a cover fitted, which was rectangular and made from a translucent tarpaulin material, held down by ties – no, not neck ties!!

Hmm, we thought, we could adapt this idea for our pond. So having obtained all the details, we phoned the company.  “We need a full size template of the pond size” was the request from them - so we provided one made from old rolls of wallpaper. Have your answers ready at the next Club meeting on how this was done!

Off to the tarpaulin company we went, complete with template, to find out that they made covers for commercial vehicles, boat covers, banners and sports nets etc.  After explaining the details of what we wanted – a Koi pond cover with a skirt all around, with feeding hatches and a sleeve down the centre - they scratched their heads and said “if we work to your template and it doesn’t fit, you will blame us!” - but if I used the template and marked out on the tarpaulin where I wanted it cut,  they would be happy to do it, as it would then be all MY fault if it didn’t  fit!    So we proceeded on this basis.

The cover fitted perfectly and has been in use every winter since 1998. As you will see from the photos it follows the Circus Big Top principle. The skirt is held down by a bungee cord threaded through eyelets, which in turn, are held in place by upside down plastic coat hooks fixed to the wall of the pond. The centre sleeve is used to keep in place two timber battens. The battens are then pulled up by three lengths of window cord using hooks and turn buckles fixed to the pergola. It’s a two man – oops -  person job to put it in place and takes just over three quarters of an hour – including various discussions on how we did it last time!!!

One thing we did differently this year was to bring the cover inside the night before we put it on, and left it propped up against a radiator in the utility room to warm, as being folded up in the garage at this time of year makes it stiff to unfold and manoeuvre. Warming it seemed to do the trick, as this year, it went on much easier and was more flexible to handle.  When not in use, the cover is folded up to about 3 ft x 18“x 12”  and goes in the garage roof. The cover cost £158.62 in 1998 from J. Clemishaw & Co., Barnbrook Street, Bury. Tel 0161 764 4614.  We would certainly ask them again, whenever we need a new cover.

By the way, it helps if you have a pergola over your pond for this type of cover !!!

Allan Leighton

Pond cover – own design and construction made with 16mm polycarbonate.


Right: Pond covered ready for winter, early October as outside temperatures began to drop, plus the fact that a couple of Koi needed treatment at the same period.


Pond heated at 20°C - 68°F but, when fish which are being treated are OK, I will drop the temperature to around 13°C – 55°F for the winter period.


Harry Smith
The company that supplied it are called Aqua Tunnels.

I got it out of December 2008 Koi magazine but they have an article in December 2009 edition (page 3).
What it says on the tin is exactly the product you get. I got mine made to measure at 15 foot square for £289 and it took about 4 hours to build - excellent product.