21 oz Stop Yellow
Product Overview
A proven choice for eradicating stubborn yellow and mustard algae blooms that resist standard chlorine levels.
Regal Stop Yellow utilizes a 99% Sodium Bromide formula to accelerate the oxidation process, specifically targeting resistant strains like yellow, pink, and brown algae. In our experience, this 21 oz treatment is the standard specification for pools where high cyanuric acid levels have rendered normal sanitizing ineffective. By following the application with 2 lbs of shock or 2.5 gallons of liquid chlorine, you create a powerful bromide-based sanitizer that clears the water within 24 hours.
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Benefits & What Makes It Different
99% Sodium Bromide Formula
This high-concentration formula converts your chlorine into a more aggressive bromine sanitizer to kill algae that chlorine alone cannot touch.
CYA Independent Performance
Unlike standard algaecides, this product reliably handles blooms even when cyanuric acid levels are high, preventing common 'chlorine lock' issues.
10,000 Gallon Treatment Capacity
Each 21 oz pouch is pre-measured to treat up to 10,000 gallons, making it a straightforward solution for residential pool recovery jobs.
Product Details
Sodium Bromide 99%
21 oz per 10,000 gallons followed by 2 lbs of shock or 2.5 gallons of liquid chlorine.
Compatibility
- Compatible with all chlorine and salt systems
- Do not mix directly with other chemicals
- Requires pH to be between 7.2–7.6 for maximum efficacy
When To Use This
Pro Tip
Before adding the 21 oz pouch, brush the affected areas thoroughly to break the algae's protective layer; this allows the bromide to penetrate the bloom much faster. In hot climates where chlorine burns off quickly, maintaining a pH of 7.2–7.6 is critical for this product to work.
Common Questions & Instructions
How soon can I swim after using Regal Stop Yellow?
You should wait until the free chlorine level returns to the ideal range of 1–3 ppm, which typically takes at least 24 hours after the required shock treatment is added.
Does Stop Yellow work in saltwater pools?
Yes, it is compatible with all chlorine-based systems, including salt chlorine generators, and helps clear green, yellow, and pink algae regardless of the sanitation method.
Why do I need to add shock 5 minutes after Stop Yellow?
Sodium bromide requires an oxidizer to activate; adding 2 lbs of shock or 2.5 gallons of liquid chlorine triggers the chemical reaction necessary to kill the algae effectively.
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.
