Pentair Rainbow 16 oz OTO #1 Solution R161056
Pentair
SKU: R161056
Pentair Rainbow OTO #1 Chlorine & Bromine Test Reagent, 16 oz | R161056
The Pentair R161056 Rainbow OTO Solution #1 is a genuine Pentair replacement water testing reagent designed for measuring chlorine and bromine sanitizer levels in swimming pools and spas. Supplied in a convenient 16-ounce bottle, this Orthotolidine (OTO) testing solution is ideal for professional pool service technicians, commercial pool operators, and homeowners who perform frequent water testing.
Designed for compatible Pentair Rainbow water testing kits and color comparators, OTO Solution #1 produces a yellow color reaction when added to pool or spa water containing chlorine or bromine. The resulting color is compared with the test kit's reference scale to determine the approximate sanitizer concentration.
The larger 16 oz bottle provides a convenient refill supply for maintaining smaller reagent bottles and supporting routine pool and spa water testing.
Product Features
- Genuine Pentair Reagent: Original manufacturer replacement testing solution.
- 16 oz Bottle: Larger container ideal for frequent pool and spa water testing.
- OTO Solution #1: Orthotolidine-based reagent for chlorine and bromine testing.
- Color-Matching Test: Produces a yellow color reaction for comparison with compatible sanitizer test scales.
- Pool & Spa Applications: Suitable for compatible swimming pool and hot tub water testing kits.
- Professional Maintenance: Convenient size for pool service technicians and commercial facilities.
- Replacement Test Reagent: Allows compatible test kits to be refilled without replacing the entire testing system.
- Easy to Use: Works with compatible drop-testing procedures and color comparators.
Product Specifications
- Manufacturer: Pentair
- Brand: Pentair Rainbow
- Manufacturer Part Number: R161056
- Distributor Part Number: RAI-45-810
- Product Type: Pool & Spa Water Testing Reagent
- Reagent: OTO Solution #1
- Chemical Indicator: Orthotolidine (OTO)
- Testing Application: Chlorine and Bromine
- Container Size: 16 Fluid Ounces
- Container Type: Bottle
- Test Method: Colorimetric / Color Comparison
- UPC: 788379003128
- Package Quantity: 1 Bottle
What Does OTO Solution Test?
OTO Solution #1 is designed for use in compatible pool and spa testing kits to provide an approximate measurement of chlorine or bromine sanitizer levels.
When the reagent is added to a properly collected water sample, the solution develops a yellow color. The color intensity is compared with the appropriate reference scale on the test kit.
- Chlorine Testing: Provides an approximate total chlorine reading using a compatible OTO comparator.
- Bromine Testing: Provides an approximate bromine reading using a compatible bromine test scale.
- Routine Water Monitoring: Helps pool owners and service professionals monitor sanitizer conditions.
Important: OTO testing does not distinguish free chlorine from combined chlorine. For separate free and combined chlorine measurements, use an appropriate DPD or FAS-DPD test method.
Compatible Pentair Rainbow Test Kits
Pentair OTO Solution #1 is used with compatible Rainbow testing systems, including:
- Pentair Rainbow Model 756 Test Kits
- Pentair Rainbow Model 752 Test Kits
- Pentair Rainbow Model 78HR Test Kits
- Other compatible Rainbow testing systems specifying OTO Solution #1
Compatibility Notice: Verify that your testing kit uses OTO Solution #1 before ordering. This reagent is not interchangeable with DPD chlorine reagents or phenol red pH testing solutions.
How to Use Pentair OTO Solution #1
- Rinse the testing comparator or sample cell with the water being tested.
- Fill the sample chamber to the designated water level.
- Add the number of OTO reagent drops specified by the test kit manufacturer.
- Cap and gently mix the water sample according to the test kit instructions.
- Allow the specified reaction time for the yellow color to develop.
- Compare the sample color against the appropriate chlorine or bromine reference scale.
- Record the approximate sanitizer concentration.
- Rinse the sample chamber after testing.
Testing Note: Always follow the instructions supplied with your specific testing kit. Required sample volume, reagent quantity, and interpretation may vary between comparator models.
Benefits of the 16 oz Refill Bottle
The Pentair R161056 provides a larger supply of OTO testing reagent compared with the smaller bottles commonly packaged with residential pool test kits.
- Convenient for frequent pool and spa water testing.
- Ideal for professional pool service routes.
- Useful for refilling compatible smaller reagent bottles.
- Helps reduce the need to purchase replacement reagents frequently.
- Allows compatible testing equipment to remain in service longer.
Related Pentair Water Testing Products
Complete your pool and spa water testing supplies with these related products available from Aqua Pool Supply.
- Pentair R161025 – OTO Solution #1, 1 oz – Smaller version of the Pentair OTO chlorine and bromine testing reagent for compatible pool and spa test kits.
- Pentair R161126 – Phenol Red pH Test Reagent, 16 oz – Genuine Pentair pH testing solution with chlorine neutralizer for compatible pool and spa water test kits.
- Pentair R151196 – Rainbow 756 Bromine & pH Test Kit – Complete water testing kit with a color comparator and reagents for monitoring bromine and pH levels.
Additional Pool Water Testing Reagents
Browse our Replacement Pool & Spa Test Reagents collection for additional chlorine, bromine, pH, alkalinity, calcium hardness, and cyanuric acid testing supplies.
Reagent Storage and Maintenance
Proper handling and storage help maintain the reliability of pool and spa testing reagents.
- Store in a cool, dry location away from direct sunlight.
- Keep the bottle tightly closed when not in use.
- Avoid exposing the reagent to excessive heat or freezing conditions.
- Do not allow the bottle opening or dropper to contact pool water.
- Do not return used reagent to the original bottle.
- Follow the manufacturer's expiration and replacement recommendations.
- Keep testing reagents away from children and pets.
Package Contents
Includes: One (1) Genuine Pentair Rainbow R161056 OTO Solution #1 Chlorine & Bromine Test Reagent, 16 oz Bottle.
Important: This listing includes the OTO reagent bottle only. Color comparators, complete test kits, sample containers, and additional testing solutions are sold separately.
Testing Limitations: OTO provides an approximate sanitizer reading and does not separately measure free and combined chlorine. Use an appropriate DPD or FAS-DPD test kit when those measurements are required.
Chemical Safety: OTO reagent contains chemicals that require careful handling. Avoid contact with skin and eyes, do not ingest, and follow all manufacturer label and safety data sheet instructions.
Shipping Notice: OTO testing reagents may be subject to hazardous-material transportation restrictions. Ground shipping may be required, and air shipment may be prohibited.
Questions about returns? View our return policy.
Hours Of Operation:
Monday - Friday: 7:00 am to 5:00 pm Phoenix Time
Saturday: 8:00 am to 2:00 pm
Sunday: Closed
- We do not ship on Saturday or Sunday.
- Orders totaling more than $300 will require signature confirmation upon delivery.
- We process and prepare orders for shipment within 1 business day. Please note that many other pool supply retailers require 3–5 days of handling time before shipping.
- Orders placed after 1:00 pm Phoenix Time may not be eligible for same-day shipment.
- Expedited shipping options are available at checkout.
Return Policy:
- Products that are received damaged will receive a refund in store credit.
- Most products are eligible for return within 30 days of receipt, except where noted below.
- To initiate a return, please complete an RMA form prior to sending your item back.
- Original shipping costs are non-refundable and will be deducted from the return credit.
- Items returned missing accessories or original packaging, or that are not in the same condition as received, may be subject to a restocking fee of up to 100% depending on the condition of the item upon return.
- Some returns will be charged an automatic 15% restocking fee.
- We are unable to issue refunds for items that have been damaged or rendered inoperable due to installer error.
- Please complete the return form to receive your RMA number and return shipping label.
- Chemical products are not eligible for return under any circumstances.
- The Pentair Colorsync 618031 is not eligible for return.
- Pool cleaners are not eligible for return.
- Opened seals and o-rings are not eligible for return.
- Capacitors are not eligible for return.
- Plastic popup tools are not eligible for return.
- Automation components and circuit boards are not eligible for return.
- If a light is returned due to a reported malfunction and is found to be fully operational upon testing, return shipping costs and a restocking fee will be deducted from the refund.
- Orders refused at the time of delivery will be subject to the original shipping costs being deducted from the refund.
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