Sensafe Industrial Test Systems | Ozone Check Test Strip 481234 | 0 - >0.5ppm Range | Bottle of 50 | Made in USA | Lowest Detection Levels | 30-Second Test | Drinking Water, Restaurants, & More

I recently replaced my ozone generator in my hottub. I used to be able to detect the ozone odor in the bubble stream but not anymore so I purchased these strips to test for ozone. I received the product tonight and I had read some reviews saying it read the same no matter what so I ran a side by side test. I took two large shot glasses (directions say about 2 oz) and filled one with hottub water and the other with hot tap water and followed the instructions for testing both at the same time. The tap water showed yellow (no ozone) and the hottub dark green (max ozone reading). So the strips work and so does my ozone gererator!

Did exactly what I needed

Definitely works. Purchased to test the output of a 1-year old ozone generator I suspected of not working. Testing confirmed no ozone present. Installed new generator, ozone definitely present (smell....) & strips give a positive test. But I found it hard to match the shade of green. Had best results when I did a "control" strip using tap water. (See attached photo). Left side was plain tap water, the one on right was the hot tub. Appears to be on the lower end of the scale. If you need to know an *exact* number for some reason, these are a challenge to read. If you just need a yes/no answer on ozone, they work well. Price was reasonable & I'll definitely buy again.

I've used these strips and received the appropriate color however other times I getting a bluish color? Has anyone else had this same reading?

Doesn't work. I returned it and got my money back. Don't waste your money. I tested my 5-year old chlorinated hot tub that has an ozonator that only lasts about 5 years. Test strip indicated it has ozone. I then tried it on an 18-year old hot tub treated with bromine and it also indicated it has ozone, even though it has no ozonator. I tried dipping the strip in filtered reversed osmosis drinking water and it said no ozone. I then sprinkled some chlorine in the water and let it disolve and now the strip says it has ozone!!