Pond Blanket Weed Controller


Our Water-King blanket weed controller for ponds controls blanket weed by causing its cells to expand and burst, or shrink and die. It does this by disrupting with the equilibrium between the calcium ions in the pool and those within the blanket weed itself and preventing excess solution from passing the cells membrane upsetting the cell’s metabolism.

Several methods have been used to control the problem of blanket weed, Water-King is the original and best of the electronic blanket weed controllers. It will not eradicate blanket weed completely, but simply to control it.



SKU: 016 Category:

How the Unit Works

Once the unit has been installed correctly on the pond system it will pass an electronic signal which will interfere with the calcium ions in the water. Blanket weed is a long filamentous structure and calcium plays an important role in the strength and structure of the membrane which is responsible for controlling the nutrient intake to the cell. The electronic signal will disrupt the equilibrium between the calcium present in the solution and the calcium in the cell membrane upsetting the cell metabolism. The membrane will have no means of preventing excess solution from entering or exiting the cell, and this means that the cell will either expand and explode, or shrink and die.Initially the process will encourage growth and the weed will expand, but once the water reaches a “super” conditioned state, the weed will begin to die away. The Water-King will control the growth of the blanket weed although it may not remove it completely.


The unit can be fitted on pipes up to 50mm in diameter and should be installed as close as possible to the pipe. The unit will operate on any normal type of pipe material, including corrugated, plastic and BSP (waste pipe). The pipe to be treated must be full of water at all times which means that water must be flowing under pressure. A pump will cause electro-magnetic interference with the signals generated by the Water-King and installation immediately prior to a pump should be avoided. The optimum location is after the pump, filters and U.V. treatment. The Water-King will also extend the life of the quartz sleeve in the U.V. system by keeping it free of scale deposits in hard water areas. A period of 7 to 8 weeks should be allowed from installation before the full effects of the Water-King may be seen.

Do I need to Do Anything Else?

It is important that you monitor the conditions of your pond water during this time as high nitrate levels and pH fluctuations will cause the blanket weed to continue to grow. This is especially important if your pond is constructed of concrete as lime may leach into the pond water and cause a variation in the pH level. We recommend that the nitrate level should be kept at around 25ppm or lower. It may be higher than this, depending upon the quality of the mains water and the filtration system installed on the pond. If you are in any doubt then seek advice from your local stockist.We recommend that any dead or dying blanket weed is removed in order to prevent de-oxygenation and clogging of filters. Regular ammonia, nitrite and nitrate tests should be carried out during this period. Ponds with excess amounts of decaying material can suffer from a disruption of the Nitrogen Cycle, so a water change may be required. It is also advisable to keep feeding down to a minimum. Uneaten food, as well as dead weed left in the pond will encourage the return of blanket weed. Blanket weed on a waterfall will take longer to be effected by the Water-King because of high light levels and oxygen.In some situations blanket weed growth can increase within the first two to three weeks of operation. This excess growth will cease when the unit has “super” conditioned all of the pond water.

Maintenance and Trouble Shooting

The Water-King needs no maintenance or servicing but do check occasionally to see that the light is flashing.

IP Rating IP8
Splash Proof Yes
Transformer External to Unit
Transformer Rating Not weather proof
100 Day Money Back Guarantee Yes
1 Year Warranty Yes
Maximum Pipe Diameter 50mm

Free UK delivery on all orders.

​Water-King orders are fulfilled by Royal Mail on their 1st Class Signed For service, delivery is expected to be 1 to 2 working days (including Saturday).

Any orders purchased before 5pm, Monday to Friday, will be dispatch the same working day, any orders after this will be dispatched the following working day.

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