A UV sanitizer is a chamber in the pool plumbing that exposes water to ultraviolet-C light as it passes through. UV-C damages the DNA of bacteria, viruses, algae spores and protozoa, so they cannot reproduce. That includes Cryptosporidium, a chlorine-resistant parasite that is a major cause of recreational water illness and can survive for days in properly chlorinated water. UV also breaks down chloramines, the compounds behind that stinging "chlorine" smell at indoor pools. Like every supplemental system, UV leaves no residual, so the pool still needs chlorine or bromine.
This category covers UV sanitizer systems and their wear parts: complete UV units for residential and commercial pools, replacement UV lamps, quartz sleeves, ballasts and O-ring kits. Builders spec UV on new residential pools for owners who want a lower-chemical feel, service companies add it for customers with skin and eye sensitivity, and commercial operators use it to help meet health-department expectations around Cryptosporidium and combined chlorine.
Disinfection depends on dose, which is UV intensity multiplied by exposure time, measured in millijoules per square centimeter (mJ/cm²). Commercial and public pool guidance, including the CDC's Model Aquatic Health Code, generally calls for secondary UV systems validated to deliver a dose that achieves a 3-log (99.9 percent) reduction of Cryptosporidium, often cited at around 40 mJ/cm² at the system's rated flow. Residential units are commonly sized for a stated dose at a maximum flow rate. Because dose falls as flow rises, a unit that works at 40 gpm may underperform at 80 gpm.
Several things reduce the delivered dose: high flow, a dirty or scaled quartz sleeve, an aging lamp and cloudy water. Water clarity is measured as UV transmittance (UVT); clear, well-filtered pool water lets more UV through than turbid water.
| Factor | Effect on UV Dose | What to Do |
|---|---|---|
| Flow above rating | Lower dose; less exposure time | Size up or install a bypass with a flow meter |
| Aging lamp | Gradual loss of output | Replace on the maker's hour interval |
| Scaled or fouled sleeve | UV blocked before reaching water | Clean or replace sleeve; keep calcium and pH balanced |
| Cloudy water (low UVT) | UV absorbed by particles | Fix filtration and chemistry first |
| Hot equipment room | Shorter ballast life | Shade and ventilate equipment |
HVAC365 stocks brand-new UV systems, lamps and quartz sleeves in original packaging with full manufacturer warranty. Product pages list flow ratings, connection sizes, lamp wattage and part numbers so you can match a replacement lamp or size a new system with confidence. Orders ship in 1-2 business days. If you are not sure which lamp or sleeve fits an existing chamber, send us the unit's model information and we will help cross-reference it.
No. UV treats only the water passing through the chamber and leaves no residual. The pool still needs chlorine or bromine to sanitize water in the pool itself.
Follow the manufacturer's rated life, commonly around a year of continuous run time for low-pressure lamps. Replace on schedule even if the lamp still glows, because UV output drops well before the lamp fails.
Yes, at an adequate dose. UV is one of the few practical ways to inactivate Crypto in pool water, which is why it is common on commercial and public pools.
Check the quartz sleeve for scale, confirm flow is within the unit's rating and verify water clarity. Indoor air handling and breakpoint chlorination also play a big part in chloramine control.
Yes. At low speeds flow is lower, which actually raises dose. Size the unit for the highest flow you will run for long periods, and check that the system's flow switch or interlock works at your low speed.
Typically after the filter, so clean water passes the lamp, and before any chlorinator or salt cell. Heaters are usually upstream as well. Follow the manufacturer's diagram and leave room to service the lamp and sleeve.
Yes, periodically. How often depends on calcium, pH and iron levels. Inspect it at each lamp change at minimum.
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