United Chemical Pool Stain Treat container with red label and white cap showing product name and usage details
white cylindrical plastic bottle of United Chemical Stain Treat 2 lb with detailed usage and storage instructions on label
United Chemical Stain Treat 2 lb white plastic bottle with red and blue label showing precautionary statements and first aid instructions

United Chemical Stain Treat, 2 lb | PST-C12

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SKU: PST-C12

United Chemical Pool Stain Treat - 2 Lbs

You work hard to keep your pool looking new. Don’t let iron stains spoil your effort.

Iron metal can enter the pool from source water (such as wells), fertilizer runoff, and dirt getting into the pool. When iron gets oxidized, it drops out to form tan to rust-colored stains on your pool surface.

Pool Stain TreatⓇ is formulated to remove and sequester iron stains from any pool surface quickly. Just add 2 lbs dissolved in a bucket of water per 20,000 gallons of water and watch the iron stains disappear, leaving a pool that looks new again.

Have a spot stain on white plaster, fiberglass, or vinyl? You can also use a Pool Stain TreatⓇ spotting bag (sold separately) directly on the stain to remove it—sometimes in just a few minutes. 

Pool Stain TreatⓇ doesn’t just remove stains; it prevents them, too. Add 1lb per 20,000 gallons per month to never worry about stains again.

Don’t let iron and organic staining ruin your beautiful pool - remove and prevent it with Pool Stain TreatⓇ.

Perfect for startup stain prevention.

Baquacil/Softswim compatible.

Works 40-60 days on all surfaces.

Features and Benefits:

  • Use - stain removal/prevention, remove any type of stain from any swimming pool
  • Compatible with - all types of swimming pool surfaces
  • Chemical type: granular
  • 2 lbs. Bottles - also available: 4 ounce "spotting bag"
  • Dosage rate - 2 lbs. Per 20,000 gallons of pool water

Directions for Use

Spotting Bag (sold separately)

Place the inner mesh bag over the area of the stain. For walls and slopes, pin the bag in place using a pool brush. Allow the bag to sit on the stain for 24 hours. DO NOT PLACE SPOTTING BAGS ON COLOR PLASTER, EXPOSED AGGREGATE, OR PAINTED SURFACES.

Stain Removal
  1. Lower the chlorine reading to 1ppm or below by either abstaining from adding chlorine or by using a chlorine neutralizer.
  2. Add 2 pounds (1 bottle) per 20,000 gallons of pool water in the following manner:
    • For Colored Plaster, Painted Surface, or Wide Spread Staining: Dissolve in a bucket of water, then broadcast evenly
      across pool surface to prevent streaking.
    • All Other Surfaces: Add the product directly to water in the area of the stain.
Prevention

Add 1lb per 20,000 gallons every 30 days to prevent the recurrence of staining.

Additional Information

Dimensions 3.25 × 3.25 × 9.25 in
Product Type

Stain Remover, Stain Preventative

Compatible Sanitizers

Chlorine, Salt, Bromine

Compatible Surface

White Plaster, Color Plaster (pre dissolve), Exposed Aggregate (pre dissolve), Fiberglass, Vinyl

Dosage

1 Spot Bag treats a 1 ft radius, 2lbs per 20,000 gallons (stain removal), 1lb / 20,000 gallons / month (prevention)

Size

4 oz. Spotting Bag, 2 lb. Bottle

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More about Pool and Spa Chemicals for Water Maintenance

Buyer's Guide: Pool and Spa Chemicals for Water Maintenance

Tier 1: The Foundation (Water Balancers)

  • Best For: Preventing "pH Bounce" and protecting pool equipment from erosion.
  • Look For: [Alkalinity Increasers] to stabilize your water foundation.
  • Expectations: Prevents rapid chemistry swings; essential before adding other treatments.

Tier 2: The Front Line (Sanitizers)

  • Best For: Daily bacteria and algae control to keep water safe for swimmers.
  • Look For: [Chlorine Tablets] or [Bromine] for consistent, slow-release disinfection.
  • Expectations: Requires regular monitoring to stay within the 1-3 ppm safety zone.

Tier 3: The Rescue & Polish (Pro-Grade Additives)

  • Best For: Clearing "dull" water or recovering from a heavy bather load/storm.
  • Look For: [Pool Shock] or [Water Clarifiers] to oxidize waste and sparkle the water.
  • Expectations: High-potency formulas that provide immediate visible results.

Complete Your Pool Care Routine

Essential Pairing
Pool Test Kits and Water Analysis Tools

Accurately measuring your current levels is the only way to know which chemicals to add without over-treating your water.

Shop Pool Test Kits and Water Analysis Tools
Highly Recommended
Pool and Spa Algaecides for Algae Control

Adding a preventative dose of algaecide weekly provides a secondary layer of defense when your sanitizer levels naturally dip.

Shop Pool and Spa Algaecides for Algae Control
Pro Tip: Don't Forget
Pool Clarifiers for Water Clarity

These specialized formulas coagulate microscopic debris into larger clumps, allowing your filter to remove "cloudiness" that chemicals alone cannot fix.

Shop Pool Clarifiers for Water Clarity
Technician's Guide: Pool and Spa Chemicals for Water Maintenance +

The Science of a Perfect Swim

Maintaining your pool or spa isn't just about adding chlorine; it’s about managing a delicate ecosystem where chemistry meets comfort. Pool and Spa Chemicals are the tools you use to keep water safe, clear, and non-corrosive. When these levels are out of sync, you risk more than just green water—you risk skin irritation, cloudy "milk" water, and expensive damage to your heaters and pumps.

The secret to easy maintenance is the Langelier Saturation Index (LSI) logic: balancing your water so it is neither "hungry" (acidic/corrosive) nor "oversaturated" (scaling). By mastering the basics of Sanitizers, pH Balancers, and Alkalinity, you ensure that your chlorine works at 100% efficiency. Without proper balance, even a pool full of chlorine can still grow algae. This collection provides the professional-grade formulas needed to protect your family’s health and your backyard investment.

Common Questions +

Q: In what order should I add my maintenance chemicals?
A: Always start with Alkalinity first, as it acts as a "buffer" for your pH. Once alkalinity is set, adjust your pH Levels, and finally add your Sanitizer or shock.

Q: Why does my pool smell like strong chlorine if the levels are "fine"?
A: That "pool smell" is actually caused by Chloramines (combined chlorine), which form when chlorine is used up. It means you actually need more chlorine or a Pool Shock to break those bonds and refresh the water.

Q: Can I use pool chemicals in my hot tub/spa?
A: Generally, yes, but be cautious of concentration. Spas have much less water and higher temperatures, which causes chemicals like Bromine or chlorine to react faster. Always follow spa-specific dosing on the label.

Q: How often should I test my water chemistry?
A: For active pools, test for Chlorine and pH at least 2–3 times per week. Total Alkalinity and Calcium Hardness should be checked once a week or after heavy rain.

Q: What is the ideal pH range for a swimming pool?
A: You should aim for a pH Level between 7.4 and 7.6. This is the same pH as the human eye, ensuring maximum comfort and preventing equipment corrosion.


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