Why Suction Side Ozone Introduction Doesn’t Work

August 22nd, 2012

For many, many years, professional pool builders and managers agreed that ozone sanitation systems should use venturi injection of ozone for maximum benefit vs. cost.  Now, some in the industry have promoted a method called ‘suction-side ozone introduction’ as a replacement because it is simpler to install.

You need to know the facts about these two approaches to pool ozone sanitation to see why the venturi injection method is superior.

Venturi Injection vs. Suction-Side

The basic difference is that the venturi injection method uses the fail-safe vacuum injection method to dissolve ozone in the pool water on the return line. The suction-side method simply pipes the ozone into the pool pump on the supply side of the impeller.

The argument the suction-side advocates make is that the venturi injection method requires low backpressure to work, and is difficult to install with some pool equipment like in floor cleaners.  They claim that the suction-side method is easy to install without retrofitting any other components. Further, they claim that the ozone introduced this way is more (or at least equally) effective compared with venturi-injected ozone.

They are wrong for several reasons:

The venturi injection does require relatively low backpressure to work, but well engineered systems (like DEL’s) are designed to work with pressure gradients that are commonly supplied by today’s pumps and plumbing systems.  Even where significant backpressure might be created by complicated downstream plumbing like in floor cleaning systems, good design can preserve all the power of the venturi injection.

More importantly, the claim that suction-side introduces the ozone as efficiently as the venturi method is simply not true.  In fact, an independent 3rd party testing agency found that the suction side method was only able to introduce enough ozone to kill only 2/3 of E.coli in a sample of water in 30 minutes..  With the venturi injection method, 99.99% of the E. coli was killed in 30 minutes or less using the identical ozone generator.

In other words, the suction-side method is ineffective relative to the venturi method in doing the one thing you want it to do:  make your pool water safe.  It’s no wonder that suction-side advocates avoid claiming that their sanitation systems qualify as a disinfectant.  In fact, venturi injection systems by DEL are both oxidizers AND disinfectants.

Other Flaws in the Suction-Side Method

There are a couple important mechanical reasons the suction-side method does not work well.

First, by introducing the ozone on the supply side of the pump impeller, suction-side systems subject the ozone to the violent turbulence of the impeller.  It is well known that this much turbulence will cause the ozone molecules to decompose, leaving behind ordinary oxygen.  While oxygen is a good element in the pool water, it is not a powerful oxidizer or disinfectant.  This may be one reason why the suction-side method does not compare well on the microorganisms tests.

Second, suction-side systems do introduce gases into the pool filter.  As many law firms can attest, these accumulations of gases can lead to powerful explosions when the pressure builds up to overwhelm the filter dome attachments.  Suction-side systems use bleeder hoses to relieve this off gas, but if these components fail for any reason, the possibility of an explosion exists.

Venturi Injection is the Cost-Effective Pool Sanitation Method

For more information about this important topic, see our article on venturi injection vs suction-side ozone introduction.  Choose the venturi method for effectiveness and peace of mind.



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