What’s the Best Pond UV Clarifier for your Garden Pond

What is a UV Clarifier

A UV Clarifier is used to clear green water from your pond, it’s not a filter but it works in conjunction with your filter system, you can fit it before or after your filter.

It has a chamber that holds a UV (ultraviolet) lamp protected by a quartz sleeve, water from your pond is drawn through the chamber where it’s exposed to the UV light, the water is then pumped back into your pond.

How do they work

Single cell algae are the culprits that turn your pond water green, they are so small they escape your filter system, a UV Clarifier uses a very strong UV lamp to kill the single cell algae, the dead algae will clump together making them bigger and easier for your filter system to catch them which will help keep your pond nice a clear.

They only kill single cell algae, it doesn’t kill string algae (blanket weed).

Choosing the wattage

UV Clarifiers come in different wattages, the bigger the wattage the more powerful the Clarifier.

You can buy them from about 7w to 110w, the size of your pond will dictate which size to go for.

Below is a selection of budget, mid-range and top end UV Clarifiers for your pond.

All Pond Solutions UV Clarifier 7w-72w

These UV Clarifiers from All Pond Solutions are very well priced if you’re looking for a budget clarifier for your pond.

There are 7 different sizes in the range, 7w to 72w, making them suitable for small ponds right up to large ponds.

There’s a helix fitted inside each unit, this spins the water around the quartz sleeve giving more exposure to the UV lamp.

Three inlet/outlets are available on all but the smallest 7w model which only has two, this enables you to run the clarifier to your filter and a waterfall, or two waterfalls if you wanted too.

They all come with stepped inlet and outlet tails for different sized hoses, 13 and 19mm for the CUV-207, and 19, 25, 32 and 38mm for the rest. 

There’s an option (apart from the CUV-207 model) to replace an outlet with a clear glass port to check the operation of the UV lamp, but they all have indicators to see the lamp so it’s not really necessary.

The smallest CUV-207 model has clear tails, this allows you to see if the UV lamp is on and working, the CUV 209 has a clear window on the end of the unit to see if the lamp is on, the rest have a transparent strip running around its centre or an indicator on the top and side to check if the lamp is working, check it at night when it’s dark, it can be a bit hard to see it in the daytime.

They come with a safety cut off switch which turns the power off if you remove the ballast.

They are designed to to be used externally so must not be submerged, they come with pre-attached brackets to fix them apart from the 211 model where you have to attach them (they are supplied).

Cable length is 2.5 metres for the CUV-207 and 5 metres for all the rest (the CUV-272 has 2 x 5 metres).

They all come with a 1-year guarantee, and they recommend you change the lamp every 12 months.

Specifications:

  • CUV-207: 7w lamp, for ponds up to 2000 litres, at flow rate of 1200 litres per hour.
  • CUV-209: 9w lamp, for ponds up to 4000 litres, at flow rate of 1500 litres per hour.
  • CUV-211: 11w lamp, for ponds up to 7000 litres, at flow rate of 1700 litres per hour.
  • CUV-218: 18w lamp, for ponds up to 12000 litres, at flow rate of 2500 litres per hour.
  • CUV-224: 24w lamp, for ponds up to 16000 litres, at flow rate of 4500 litres per hour.
  • CUV-236: 36w lamp, for ponds up to 20000 litres, at flow rate of 6000 litres per hour.
  • CUV-272: 2 x 36w lamp, for ponds up to 35000 litres, at flow rate of 6000 litres per hour.

You can purchase these All Pond Solutions clarifiers from Amazon.co.uk, they usually have the full range in stock.

Blagdon Pro UV Clarifier 18w-72w

These Blagdon Pro UV clarifiers are priced as a mid range option.

Just 4 in the range, 18w-72w, but they have covered the popular sizes.

They can be used before your filter system or after your filter system, it’s entirely up to you and they can be connected together for future expansion if needed.

They come with stepped inlet and outlets, 19, 25, 32 and 38mm and 43mm solvent weld fittings as show in this image.

Blagdon claims to have twice the UV output of conventional UV units by utilising an advanced power compact UV lamp system.

They recommend you replace the lamp every 6 months, and suggest you do this once a year in spring.

They come with built in brackets for fixing and 5 metres of power cable (2 x 5 metres model 64800).

Theres a lamp indicator window in the cap that holds the lamp in place, this will show you if the lamp is on and working, you will probably need to wait till its dark to see anything.

3 Year Guarantee.

Specifications:

  • 16200: 18w lamp, for ponds up to 16200, at a flow rate of 8100 litres per hour.
  • 21600: 24w lamp, for ponds up to 21600, at a flow rate of 10800 litres per hour.
  • 32400: 36w lamp, for ponds up to 32400, at a flow rate of 16200 litres per hour.
  • 64800: 2 x 36w lamps, for ponds up to 64800, at a flow rate of 32400 litres per hour.

You can buy them from Amazon.co.uk or pondkeeper.co.uk

Evolution Aqua evoUV Clarifier 15w-110w

The Evolution Aqua range of UV clarifirers have been completely re-designed for 2021 giving better performance and easier to service, they are priced as a high end option.

There are 6 evoUV pond clarifiers in the range 15w to 110w, all simple to install.

They can be installed before your filter system as a pump fed clarifier or after your filter system as a gravity fed clarifier, they can also be installed at any angle you choose.

You can install it with the inlet on the right and oulet on the left or the other way round, inlet on the left outlet on the right.

They come with stepped inlet and outlet hosetails for flexible hoses 19, 25, 32 and 38mm (apart from the evo110), they can also be hard plumbed using 1.5″ BSP male fittings (the evo110 must be hard plumbed using 2″ pressured pipe).

The UV lamp and quartz sleeve are packed separately and not fitted when you receive the clarifier so will need to be fitted, but one of the features is how simple it is to fit and change the lamp, quartz sleeve and ballast.

The full range of clarifiers have thermal overload protection which automatically shuts down if there is a problem and then enables a fast re-start when the problem has been cleared.

They come with 2.2 metres of power cable, and they come with stainless steel fixing brackets.

The UV lamp has a lifespan of 9000 hours, but they recommend you change the lamp at the beginning of the year.

They all come with a 2-year guarantee.

Specifications:

  • EVO15: 15w lamp, for ponds up to 15000 litres, at a flow rate of 7500 litres per hour.
  • EVO25: 25w lamp, for ponds up to 20000 litres, at a flow rate of 10000 litres per hour.
  • EVO30: 30w lamp, for ponds up to 30000 litres, at a flow rate of 15000 litres per hour.
  • EVO55: 55w lamp, for ponds up to 55000 litres, at a flow rate of 20000 litres per hour.
  • EVO75: 75w lamp, for ponds up to 75000 litres, at a flow rate of 25000 litres per hour.
  • EVO110: 2 x 55w lamps, for ponds up to 75000 litres, at a flow rate of 25000 litres per hour.

You can find the full range at bradshawsdirect.co.uk and Amazon.co.uk