Getting Crystal Clear Water with a UV Clarifier

A UV Clarifier is a piece of equipment that treats your pond water with concentrated UV light, which helps keeps the water crystal clear. Murky water is often caused by single celled alage floating in the water. The UV light kills this certain type of algae which greatly increases water clarity once gone. If installed correctly, Aqua Ultraviolet guarantees your green pond water will clear up in 3 to 5 days while using the device. Consider this piece of equipment if you want minimal pond maintenance, if you're suffering from murky green water or if your pond is subject to direct sunlight and warmer temperatures. 

For information on how to size a UV Clarifier and how the equipment works please scroll to the bottom of this page. 

8 Watt UV Clarifier

Aqua Ultraviolet UV Clarifier Sizes
Watts Clarifier Pond Size Clarifier Pump Flow Sterilizer Pond Size Sterilizer Pump Flow Price
8 1,500 Gallons 1,000 GPH 5-200 Gallons 642 GPH $204.99
15 2,000 Gallons 1,800 GPH 200-500 Gallons 700 GPH $215.99
25 4,000 Gallons 2,000 GPH 500-1,200 Gallons 1,200 GPH $289.99
40 6,000 Gallons 3,000 GPH 1,200-2,000 Gallons 2,900 GPH $431.99
57 6,500 Gallons 3,250 GPH 1,500-3,000 Gallons 3,200 GPH $451.99
80 9,000 Gallons 4,500 GPH 2,200-4,400 Gallons 3,678 GPH $729.99
114 9,500 Gallons 4,500 GPH 2,200-4,400 Gallons 3,900 GPH $877.99
120 12,000 Gallons 6,500 GPH 4,400-6,000 Gallons 4,080 GPH $1,023.99
160 16,000 Gallons 9,000GPH 6,000-8,500 Gallons 5,400 GPH $1,370.99
200 20,000 Gallons 10,000 GPH 8,500-13,000 Gallons 6,6000 GPH $1,727.99
240 25,000 Gallons 12,000 GPH 13,000-17,000 Gallons 7,200 GPH $2,089.99

Sizing a UV Clarifier 

Step 1. Determine Pond Size in Gallons
Firstly, you must figure out how many gallons you want to pump per hour in order to choose the best sized UV Clarifier. Begin by determining your pond size; do this by recording the length, width and depth of your pond and inputting those numbers into our Pond Volume Wizard. This will give you the gallons of water in your pond.

Step 2. Determine Flow Rate
Next you must determine how often you want to pump the entire contents of your pond. Generally speaking, if you have fish you will want to pump the entire contents of the pond a minimum of once per hour. If you don't have fish you can relax on that number a bit. Other considerations such as climate, quantity of fish or how much debris will fall into the pond must also be considered when choosing a flow rate for your pond. For more in-depth detail visit out Choosing a Pump Page.


Now that you know how many gallons are in your pond and how many gallons you want to pump per hour, we can now start looking for a Clarifier that matches those specs. This brings us to another question: What is the difference between a Clarifier and a Sterilizer? 

Step 3. Choose Between a Clarifier or Sterilizer 
The main difference between the two is the strength of the UV light compared to the amount of water in your pond.  As a rule of thumb, use 10W of UV light per 1000 gallons for 'clarification', and 30 watts of UV light per 1000 gallons for 'sterilization'.  As a sterilizer, the unit will eliminate green water entirely, no matter what type of pond you operate.  When used as a clarifier, the unit is said to 'control' green water, however it's recommended that ponds have at least 50% plant coverage and partial shade to cut down on algae growth.  Do you have an obvious green water problem that you're having trouble fixing or you have a good number of fish in the pond?  Then use the unit as a sterilizer.  Do you have an ecosystem water garden with no fish that's running well, but could use an extra kick to help give you water that 'polished' look?  Then using the unit as a clarifier will likely be fine.

Adding a UV Clarifier to an existing pond

To add a clarifier to an existing ecosystem you must determine your current flow rate and then choose a clarifier/sterilizer that matches those specs. Determine your flow rate by calculating the head pressure in your pond using our Head Pressure Wizard, followed by researching how much flow is generated by your equipment at that head pressure. Use that flow rate to help narrow down which unit will be best for you. Please note that adding a UV Clarifier will add head pressure to your system which will effect your current flow rate.

Does a UV Clarifier increase head pressure?

Yes, a UV Clarifier/Sterilizer will increase your head pressure. Please use our Head Pressure Wizard to estimate how much it will effect your flow rate. 

A UV Clarifier with 2" pipe has to house the UV equipment inside the pipe, leaving less than 2" for the actual water. Because of this, a 2" UV unit is usually equivalent to 1.5" pipe for head pressure calculations.

How can I decrease head pressure?

You can choose to run two UV clarifiers side by side to decrease the volume of water being forced through the unit. 

Do I have to run it year round?

The length of time you run your UV Clarifier is largely dependant on sun exposure and the temperature of the environment around your pond. Higher temperatures yield higher algae growth, thus making a sterilizer necessary to keep water clean. Once temperatures drop feel free to remove the clarifier and store inside until the temperature and sun exposure increase again.