Pentair 1 oz OTO #1 Test Solution
Product Overview
Fast, color-distinct total sanitizer readings for standard chlorine and bromine test blocks.
Pentair Rainbow OTO #1 Test Solution provides an immediate colorimetric check for chlorine and bromine levels in residential and commercial pools. Formulated to work cleanly with standard comparator blocks, this reagent (supplied in 1 oz packaging, also referenced as 0.5 OZ. on select bottle runs) gives clear yellow gradations for quick daily sanitizer monitoring.
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Benefits & What Makes It Different
Instant Visual Readings
Reacts immediately on contact with sanitizer to display clear yellow color gradients for total chlorine and bromine.
Calibrated Dropper Tip
Delivers uniform drop sizes to maintain testing accuracy and prevent false high or low readings.
Standard Cell Compatibility
Formulated specifically to match the optical color prisms on Pentair and standard 2-way or 4-way test cells.
Product Details
Orthotolidine (< 0.1%), Hydrochloric Acid (< 3.7%)
Add 4 to 5 drops to the test vial filled to the water sample indicator line
Compatibility
- Pentair Rainbow test kits
- Standard 2-way visual test blocks
- Standard 4-way comparator cells
- Chlorine and bromine sanitizer systems
When To Use This
Pro Tip
Read the test vial within 2 to 3 seconds of mixing; waiting longer allows combined chloramines to continue reacting and darken the yellow hue, resulting in an artificially high total reading.
Common Questions & Instructions
Does OTO #1 test solution measure free chlorine or total chlorine?
OTO (Orthotolidine) measures total chlorine and bromine in water samples; it does not differentiate between free chlorine and combined chloramines.
How often should Pentair OTO test reagents be replaced?
Testing reagents should be replaced annually at the start of each pool season to prevent inaccurate readings caused by heat and light exposure.
How many drops of OTO solution should be used per test?
Most standard visual test blocks specify adding 4 to 5 drops of OTO solution into the test vial filled to the water sample line.
Delivered today to your DFW neighborhood
Order this item by 2 PM Central on a weekday, and we'll have it on your driveway by evening. Same-day delivery is FREE to every ZIP in our DFW coverage area — no minimum — or it's free with our weekly service plan.
