SKU: 33815-300

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[4.7]   3 Reviews    | Write a Review

Buy Indigo® 300ppm available chlorine test strips to ensure your freshly harvested apples are free from spoilage microorganisms such as pathogenic bacteria and yeasts. A concentration of 50-200 ppm of sodium hypochlorite can typically achieve a 1 to 2 log reduction of many pathogens. However, for bacteria such as Listeria monocytogenes, known to cause foodborne illness, this is only sufficient to achieve a 0.6 log reduction. The higher range this strip which indicates 300ppm may be of benefit.

Organic production and handling regulations allow the use of sodium hypochlorite. Follow label directions for appropriate levels of apple disinfection. Then, rinse with water; our 0-10ppm residual level chlorine test strips can be used if needed to confirm adherence to guidelines.

Certificate of Analysis, Stability & SDS are available below; Certificate of Conformance on request. Be prepared for any farm or food safety audit.


Common apple tree fruit infections such as fire blight, powdery mildew, flyspeck and sooty blotch are best dealt with by pruning infected twigs & apple leaves with old cankers. Other fungi such as apple scab are best dealt with by planting disease resistant cultivars.

Be sure to clean your metal tools with a 1:10 mixture of chlorine bleach. For this, you will need our 0-1000ppm strip strip which can indicate 500ppm.

Confused about how to dilute? Use our hypochlorite (chlorine) dilution calculator to prepare any concentration of chlorine bleach disinfectant solutions & take out the guesswork.

Related information or images
Results in 5-10 seconds with readings at 25, 50, 100, 200, 300 ppm for free (available: HOCl & OCl-) chlorine bleach concentration. This strip has a detection limit of 2-3 ppm.
  • Indigo® test strips have a guaranteed minimum 3 year shelf life but are stored in desiccant lined vials so actual shelf life can be 5+ years.
  • For technical explanation, read: Sanitizer Test Strip Expiration; Good Today, Dead Tomorrow?
  • These strips measure free (available) chlorine
  • The number of strips (100) per vial is approximate.

Test Strip Documentation

Stability Statement Certificate of Analysis SDS Calibration Fluid CoA
Indigo Chlorine 300ppm Test Strip Stability Statement
Indigo Chlorine 300ppm Test Strip Certificate of Analysis
Indigo Chlorine 300ppm Test Strip SDS Calibration Fluid Certificate of Analysis

Indigo® brand chlorine test strips are Made in USA & tested for accuracy using NIST compliant standards.

Reviews (3)

The high chlorine test strips are handy for operators to measure Free Chlorine levels to ensure adequate dosages have been achieved when disinfecting watermains and cleaning storage facilities. They arrived very quickly.

— LindaT
— Indigo:

Interesting applications, thanks for the feedback.


I am glad these are packaged in a container; we have had some in the past packaged in a paper envelope (from another company), which is hard to keep dry. They work just as advertised - the only imperfection for us is that the colors are fairly similar and it can be hard to tell at a glance what the result is. Otherwise, great.

— Lettuce
— Indigo:

Thanks for the feedback. The packaging for most sanitizer test strips come in special desiccant lined containers which is explained further in: Test Strip Expiration Dates; Good Today, Dead Tomorrow?

Some of the color charts are indeed harder to read than others. Good lighting can help. Fluorescent lighting is not as contrast friendly as natural sunlight or halogen or quartz.

These Chlorine test strips are great when you need to measure Free Chlorine levels in water at high levels of concentration.
— Great product, arrived quickly.
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