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Flexiliner 18m x 12m 40 Year Guarantee Plus Underlay

SKU: FL180X120-15F
Manufacturer: Pondxpert
Was £732.24
RRP: £1,466.65
In Stock
Want this for Tuesday October 26th? Order in the next


01642 370888

Product Description

This bestselling large pond liner comes with free underlay worth £237.60.

This limited offer brings down the price of a large liner to levels never seen before. This offer includes a liner sized 18m x 12m (59' x 39') and a matching amount of underlay (216 square metres). The size and design of pond you can create with this lining is practically limitless and with a maximum depth is 1 metre you can create a project sized 15m x 9m with a volume of 135,000 litres(29,736 gallons).


  • 40 year guarantee Black colour Liner is tear-proof, rot-proof and UV-resistant

FeeFo Feedback

Pond Keeper reviews

Feedback for Pond Keeper has been compiled from 3423 customer reviews

Date Product Score Customer Comment

Pond Liner 4m x 4m 40 Year Guarantee Plus Underlay

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  • Pond Liner 4m x 4m 40 Year Guarantee Plus Underlay

item as described good quality well priced

Blagdon All-in-One Treatment (1000ml)


Service rating : The whole procedure was simple and straightforward and delivery was as promised.
Product : We'd already been raided by a heron and took steps to deter any further attacks (fluorescent fishing line around and across the pond). Then half of the fish inexplicaly died. We're no experts but, after doing some research we found we probably had too meny fish for the volume of the pond anyway. That being said they all seemed healthy enough up till then. The remainder were listless and the black ones seemed to be covered in grey mucus. After a week's treatment, carefully following the instructions provided all seem fit and healthy. They are moving around normally and eating again. Very relieved and grateful.

PondXpert Flowmaster 4500 Pond Pump


Service rating : The pump is too noisy, iíve cleaned the propeller but still noisy, I donít switch it on much.
Product : Excellent value for money but so dissatisfied with the performance.

Pro Tarpaulin 200gsm 5x4m (16x5 Inches)


Answered all questions even when not relevant to current purchase

PondXpert TripleAction 2000 Evolve (5w UVC)


Service rating : I had an issue with a pond liner and Pondkeeper refunded my payment with no fuss.
Product : Although the smallest of the range, this pump is ideal for my 2x4m pond. Good throughput and decent fountain height.

8x6 Greenseal Pondliner

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  • 8x6 Greenseal Pondliner

Their service could not have been better. Very quick to deliver and pleased with the product

8x7 Greenseal Pondliner

  • Customer also bought: .... :
  • 3x3 Greenseal Pondliner
  • Pond Fleece Underlay 8x7
  • Hutton Gold Label Black Sealer (One Shot)
  • Pond Fleece Underlay 3x3

Excellent quality products and helpful website made prurchase easy. Reasonable price and a good range of products are available.

Pond Liner 6m x 5m 40 Year Guarantee Plus Underlay

  • Customer also bought: .... :
  • Blagdon Inpond 3000 All-in-One Pond Pump (5w UVC)

Service rating : quick and excellent service
Product : strong and easy to lay and to cut to size

PondHero PondForce 4700 Filter Pump


Service rating : My problem was delt with swiftly completely to my requirements, my replacement pump arrived next day..
Product : Great product sturdy construction

25yr pondliner 15x10


Service rating : A hick-up to start with but all resolved very quickly and without question. Customer Service was easy to contact. Great product at an affordable price. Many thanks.
Product : Found the size of pond liner I needed through the calculator embede on the website. Not high-end but very good quality at an affordable price.

PondXpert Heavy Duty Sludge Net

  • Customer also bought: .... :
  • PondXpert Heavy Duty Sludge Net
  • PondXpert Throw 'n Go! Pond Gel Balls (8 for 5)
  • Natures Grub Koi Treat Mix Pond Food (1kg)

Got in contact with the firm and the customer care service was exceptionally good???? . My problem was sorted out really quickly and my pole and net was delivered the next day.

11w Single-Ended UVC Bulb (BOGOF)

  • Customer also bought: .... :
  • Tetra Pond Test 6-in-1
  • Blagdon Stress Away (1000ml)

Service rating : Aways get my pond supplies from this excellent company
Product : regular order always good quality

Pond Liner 2m x 2m 40 Year Guarantee Plus Underlay

  • Customer also bought: .... :
  • Pond Liner 2m x 2m 40 Year Guarantee Plus Underlay

Excellent service,well packaged pond liner looks good .Very pleased with purchase.

PondXpert PondMaster Sponge Collar

  • Customer also bought: .... :
  • PondXpert PondMaster Sponge Collar

Quick and efficient delivery yes I would reccomend Pondkeeper

Hozelock Cascade 1500 Fountain Pump

  • Customer also bought: .... :
  • Hozelock Cascade 1500 Fountain Pump

The pump I ordered was delivered in a timely fashion. On discovering I had ordered the wrong one I returned it and a second suitable pump was swiftly delivered. A phone cal with a query was answered promptly and helpfully.

PondXpert SpinClean 40000 Filter & UltraFlow 16000 Pump Set


Service rating : Good product easy to install with excellent customer support
Product : Very good product extremely easy to install and use.

PondXpert Flowmaster 3500 Pond Pump


Service rating : Delivery on time price good
Product : This product is very reliable the last one gave me years of service

PondXpert Preformed Pond (Tench)


Service rating : quality is good delivery good easy to set up can`t wait to stock it.
Product : good delivery excellent product very pleased

PondXpert Preformed Pond (Tench)


Service rating : Very fast and efficient service and delivery. Good quality product- Tench preformed pond is perfect size for my garden. Its straight forward to put in and the wildlife love the one I have put in at my allotment.
Product : Already covered previously.

Blagdon Stress Away (250ml)

  • Customer also bought: .... :
  • PondXpert Winter Wheatgerm (4kg)
  • PondXpert Blue Long Armed Pond Gloves (FREE with voucher: gloves)

Excellent service, quick delivery response.

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