4 UV Pool Systems Disadvantages You Must Know

inground pool with white pool plaster in open backyard on a sunny day

To the typical pool owner, just about anything other than a chlorine only disinfection system must be an improvement, right?  This is how things like salt systems and ozone systems begin their sales literature in most cases.  You may have heard of another popular alternative disinfection system though, the UV system.  The positives sound great, but what are the UV pool systems disadvantages?

How Do Ozone Pool Systems Work?

Fist, let’s refresh what a UV system is actually doing.  A UV system is exposing pool water to UV light.  This happens in a dedicated UV disinfection chamber located at the pool equipment.  In most cases, they are installed after the filter.  The chamber will have a dedicated flow direction, so water will go in one end and out the other.  As the water travels through the chamber it is exposed to ultraviolet light.  Around 99% of microorganisms which make their way into the swimming pool are neutralized when they come into contact with ultraviolet light.

Depending on the system, the UV intensity will vary.  But most residential UV systems are operating at a low intensity UV.  There are some commercial systems which operate at medium intensity. However, if you’re not careful they’ll burn the chlorine out of the water.  Hence, for simplicity sake, we stick with low intensity UV systems for residential pools.  

4 UV Pool Systems Disadvantages

While we often sign the praises of UV pool systems, they’re not without disadvantages. Through our years of building pools with UV pool systems, we’ve found 4 frequent cons. Here are the 4 most frustrating things about having a UV pool system.

UV Does Not Oxidize Water

Though the intensity of these systems is labeled as ‘low’ they still are effective at doing much of the work of chlorine.  However, this brings us to the first disadvantage of a UV system. They do not oxidize the water. While ozone systems oxidize the water and break down the non-living contaminants which lead to chloramines and burning skin and eyes, UV does none of this.  UV is only killing the microorganisms.  

UV Is Not Residual

Second, UV is not a residual.  Since the UV chamber is located at your pool equipment, as soon as the pump shuts off, the UV is no longer killing any microorganisms.  With today’s variable speed pumps, it is becoming more and more common for pools to be designed for 24 hour circulation.  But if you have a traditional pool that’s running for 8-12 hours a day, the UV is only functional when the pump is running.  When the pump is off, you’re back to relying on the chlorine residual for all your disinfection needs.

UV Requires Frequent Light Maintenance

Next in the list of UV pool systems disadvantages is the light bulbs. We recommend you replace the bulbs whether they ‘need it’ or not every 2 years.  The reason being with ultraviolet light, the bulbs will still turn on, but over time the intensity of the light diminishes.  If you wait for the bulbs to burn out, they will not be functional at a helpful intensity for some time.  For this reason, there are some people out there with UV systems who claim they no longer work, when in reality they simply need new bulbs.  

UV Lights Are Expensive

The cost of bulb replacement is another issue.  If you were to do it yourself, you can easily spend $150 on the bulbs.  Then, during the change you have to be extremely careful as you cannot under any circumstances touch the bulb with your bare skin as it’ll reduce the longevity of the bulb.  All in all, it’s a bit of a frustration if you’re trying to do it yourself.  We’d definitely suggest hiring a service company experienced with UV systems to do any bulb changes for you, which costs more but at least you know it’s being done correctly.  

If you have an Ozone system in combination with a UV system, we’d suggest changing all the bulbs every two years. This is to be certain your systems are in top operational condition.

Blue tiled backyard pool showcasing the 4 main UV pool systems disadvantages for maintenance

UV Pool Systems Disadvantages Summary

In conclusion, there are some UV pool systems disadvantages. However, we feel the positive benefit of a UV system far outweighs the negatives.  The reduction in chlorine use, especially when combined with an ozone system is enormous. 

There is a reason most modern public swimming pools and municipal drinking water systems are designed with UV and Ozone systems.  When it comes to decent water to swim in or drink, the goals are very similar.  Combining UV and ozone will reduce the amount of chlorine, and the amount of combined chlorine (chloramines) in the water.

If you want to learn more about UV pool system, here is an excellent video explaining them. We hope you now understand the pros and cons behind a UV pool system. Despite some inconveniences, we stand by adding them to your pool.