Ultra Violet Filtration vs. UltraSonic Algae Control – Technologies Compete

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There’s no question that emerging technology over the last few decades as helped pond owners create better looking ponds. Unfortunately along with all of these advances comes the inevitable confusion of what’s best for a particular pond situation.

Today I want to address two very useful tools in pond algae control, and cover their benefits along with their drawbacks in relation to one another. One has been around for a good number of years, and the other is emerging as one of the most useful tools for any size of pond.

More specifically, looking at the merits of UV filters and Ultrasound might help clear up some confusion, and a few ponds along the way, both of which are good things.

Let’s cover ultra violet filtration first.

UV filtration works by using ultra violet light to damage the cell membrane of the algae. Usually this light is housed in a tubular structure that is placed in line where water will pass through the filter and be exposed to the light.

The strength and primary benefit of a UV filter is the control of planktonic algae or green water issues. It also helps to minimize viruses that may affect fish populations. Unfortunately because other types of algae can’t pass through the filter itself, things like string algae, or pond scum will be left unaffected. With this in mind, it’s essential that a UV filter not be the only method of filtration in your pond. They can work in conjunction with a good bio-filter and between the two systems it should cover a pond’s filtration needs quite well.

A UV filter works best by having the proper size of filter for your pond’s needs and the proper flow rate of the water passing through it. Ideally you want to allow the pond’s volume of water to pass through the filter multiple times and have the UV light gradually affect the water through these numerous exposures. Issues like “dirty water” or inadequate filter size for a pond’s volume will reduce it’s effectiveness.

UV filters are relatively affordable when compared to other forms of filtration. There is the need to replace the bulbs, usually on a yearly basis is recommended, but other than that there shouldn’t be any residual costs.

So, all in all, if you have an ongoing problem with green water in your pond, ultra violet filtration can be a useful tool. It’s not an overly expensive option to add to a small pond, however the cost goes up as the pond gets larger. It’s important to remember that to get the best results, you want to install a filter that is more than adequate for your pond’s size and needs. UV light will not clear all types of dirty or murky water unless it’s coming from an algae problem, and it will not work with all types of algae you may have to deal with in your pond.

Now on to ultrasonic algae control.

Like UV systems, ultrasound has been used in a variety of industries and applications for a number of years. Sonic algae control began about ten years ago in Europe and over that time, it was inevitable that this technology would make it’s way into ponds and water gardens.

Also like UV, ultrasound works to damage or rupture the cell membrane of the algae and the simplest way to look at the process is to compare how an opera singer can literally break a crystal goblet with her voice. When the resonating frequency hits the perfect pitch the crystal shatters into pieces. Ultrasound can be targeted in the same way towards algae. When the frequency is modulated and tuned very specifically it can travel through the water and break the membrane of the algae cell.

One advantage of sonic algae control is that it can work on a variety of algae types. Green water issues can be controlled pretty quickly, usually in a matter of days. Mass types of algae such as string algae, will take longer to eradicate, but over time, the algae gets reduced and has a much harder time to develop and take off once it’s brought under control.

Ultrasound has proven to be very safe for fish and it’s easy to install into a pond. Installation might not even be right best word to describe it. One simply plugs the control box into a power supply and drops the transducer or ultrasound emitter into the water and your treatment is underway.

Ultrasonic systems can work in most sizes of ponds. There are units designed for small backyard water gardens and others which work in larger ponds and lakes.

In a cost comparison with UV, ultrasound is more costly for smaller ponds. However as the ponds get larger, ultrasonic units become more and more affordable in comparison. For example the largest sonic system available will treat a multi-acre lake and cost around $3,000. Similar UV systems to treat the same body of water may run more than ten times as much in cost!

Another potential benefit of ultrasounds is unlike UV, the ultrasonic wave will not hinder or harm beneficial bacteria in the pond. This element (bacteria) does a great deal of the legwork in terms of cleaning and balancing a pond. Ultrasound can actually help stimulate or ramp up the vitality of the existing useful bacteria which is a very positive thing in terms of overall pond health.

It should be noted that neither system will provide increased oxygen levels in a pond. Only some form of aeration can do that, but on a positive note, both treatments will work well right along with an aeration program.

So in the end, how do these two technologies stack up with one another? How do you decide which one will work best for your needs?

To be sure, if you have a small pond, say anything less than 6,000 gallons, and green water is your only problem, then ultra violet clarification makes a lot of sense. It’s considerably cheaper than ultrasound and will often take care of planktonic algae when the filter is set up properly.

If you have a small pond with a variety of algae issues, then ultrasound would tend to be a more viable option since it can take care of a wider variety of algae species. If the price is too out of line for your budget, then the use of a beneficial bacteria supplement may help reduce algae growth in all it’s varieties at a much lower cost.

As one moves into larger ponds, or those greater than 6,000 gallons, the cost of UV will climb, making ultrasound look more attractive for treating large bodies of water. Due to the fact that it treats many types of algae and helps bacteria perform better, it becomes even a stronger candidate for larger ponds.

Installation of UV often involves installing it inline with the current pump and filter system. Therefore some degree of handy work will be involved in getting the system operational. As for ultrasound, the pond owner simply has to plug the unit in, preferably mount the control panel, and drop the emitter into the pond. So if you’re into the “plug and play” routine, ultrasound would win out on this count.

As pond owners we’re fortunate to have all of this great technology at our disposal. If algae in one form or another is the main issue plaguing your pond, be sure to do a bit of research into both of these treatment options and ultimately you’re sure to find the best one to suit your situation to a tee.

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4 thoughts on “Ultra Violet Filtration vs. UltraSonic Algae Control – Technologies Compete”

  1. In regard to ultraSonic algae control, can you tell us why ultraSonic devices do not work as described in northern ponds in Michigan or maybe Indiana, but work good in southern states? In the sales literature I have read, they fail to document any reserach on different algae types and why results vary in different parts of the U.S.

  2. Hi Larry,
    This is a great question. In terms of geography and the ultrasound not working in northern areas, that’s not been the case in our experience overall. As you suggested though, there are algae types that are more hardy or stubborn and not as vulnerable to ultrasound. Usually these involve certain specific strains of filamentous algae like Spirogyra. So rather than it being a geographic issue, it’s always been more of an issue with the algae type.

    Most ponds have at least several species of algae in them at one time…visually they may not look different but they often are.

    This is why when someone is considering the use or purchase of an ultrasonic unit from us, we encourage the pond owner to send a water and algae sample to us and we then send that off to an aquatics lab to see what algae is actually present. By looking at the results it will tell us if ultrasound is a good fit for the pond’s situation. In most cases it is, and has worked well. In cases where it doesn’t fit, there are other options to use as I’ll note below.

    The other interesting thing is that when one puts ultrasound in the pond, particularly where any form of string algae is concerned, there can be a lot of work and progress going on, but it is slow going and visually you may not see much change for a good while. The sonic wave must literally bang away at the outer wall of that algae mass and kill it gradually. Sometimes, algae can grow just as fast, so in these cases it’s a good idea to try to knock the algae out first, then apply the ultrasound to keep it from reforming.

    And finally, I think ultimately it’s important to look at ultrasound or uv as one tool. It may or may not be the silver bullet solution. If it isn’t, ultrasound in particular can work in conjunction with aeration, and bacteria supplements (which are my preferred treatment options) and fit in well with those protocols.

    Thanks again for the great question.


  3. ok you say that ultrasound can work in conjunction with bacteria supplements, can uv also work well with bacteria supplements also. im thinking of a uv stystem for my pond.

  4. Hi Lisa,
    UV can work with bacteria but some of this depends on if the system is set up to be a sterilizer or clarifier. All of this depends on the flow rate of the water through the UV.

    There is an upcoming article coming out explaining this all in more detail.

    One thing we’ve found is that some folks haven’t had luck with the two together. Others who have used the Healthy Ponds system seem to do ok. I think this is because HP is continually released over a 30 day periods so the pond is “well stocked” with bacteria, even if the UV knocks some of it down on the pass through.

    Take care,

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