Free Chlorine/Bleach Test Strips, 0-1000 ppm [Vial of 25 Strips]

The color code chart is it range of purples in the test strips turned blue. I used another brand test strip that work correctly to be sure it wasn't something in my solution. I should have read the reviews because I wasn't the only one that happened to.

The concept is sensible — inexpensive single-use strips specifically for free chlorine, 0-1000 ppm range, useful for daycare compliance or sanitizing solutions — but a recurring issue in the reviews is that these strips don't produce the expected color response. Multiple buyers report the strips turning blue or staying white entirely rather than the purple-to-dark-purple progression shown on the chart. A couple verified this by testing alongside other brands that worked correctly, ruling out user error or solution issues. When they work as intended, the strips are simple and the increments are easy to read. But "when they work" is doing a lot of heavy lifting here. For daycare or food-service compliance where you actually need accurate results, that's not a minor quibble — it's the whole job. At $9 for 25 strips it's cheap enough, but the reliability concerns are real enough to warrant caution before staking compliance records on them.

on a scale of white to purple, my solution has aqua ppm of ... ?

These test strips are completely unreliable. I use several different brands for our hot tub, and while every other strip clearly shows adequate chlorine levels, these consistently come back white, showing nothing at all. They simply don't work. Even if they did, I'm not sure why anyone would buy single-purpose strips when you can get multipurpose ones for around the same price. My regular test strips measure chlorine plus four or five other important levels in one go, which makes way more sense. Skip these and get a kit that actually does the job and gives you more information while you're at it.