Stain Identification & Removal
Not sure what that stain is? Start with the cheat sheet and quick spot tests below, then follow the matching removal steps. If you’re unsure, bring a water sample in for FREE testing and help.
Stain Cheat Sheet (Fast Guess)
Use this to get close quickly, then confirm with the spot tests below.
Before You Treat (Do This First)
This prevents wasted chemicals and avoids making stains worse.
Water & Equipment Check
- Test and balance water first (pH ~7.4–7.6, alkalinity ~100–150).
- Clean/inspect the filter and run circulation.
- Brush the stain area first; vacuum after treatment.
Safety Rules
- Never mix products (wait between treatments).
- Vinyl liners: avoid leaving strong granular chlorine/acid sitting on the liner.
- If unsure, stop and call — stains can be permanent if treated incorrectly.
Quick Stain Test (Confirm It)
Try these spot tests to identify the stain type.
Organic Stain Test
- Sprinkle a small amount of granular chlorine on the stain.
- Brush it into the area.
- If it fades, it’s likely organic.
- If it doesn’t, it’s likely metal.
Metal Stain Test
- Add a small handful of ascorbic acid (or crushed Vitamin C).
- Brush it into the stain.
- If it fades, it’s likely metal.
- (Also helps many rust stains.)
Rust Stain Test
- Add a small handful of dry acid (sodium bisulfate).
- Brush into the stain.
- If it fades, it’s likely rust.
Common Causes (Why It Happens)
Knowing the source helps stop stains from coming right back.
Metals (Iron/Copper)
- Well water / high iron in fill water
- Low pH over time corroding metal parts
- Heater core corrosion or metal plumbing
- Some algaecides contain copper
Organic / Scale
- Leaves, pollen, algae and tannins settling
- Storm runoff / fertilizer or yard debris
- High calcium and/or high pH creating scale
- Poor circulation or a dirty filter
Removal Steps
Tap a section to expand the steps.
Organic Stains (Leaves / Algae / Pollen)
Typical signs: green/brown staining that fades with chlorine.
- Balance water first (pH ~7.4–7.6, alkalinity ~100–150).
- Shock and circulate.
- After circulation, lightly apply granular chlorine to the stain area.
- Brush and repeat as needed until it lifts.
- Vacuum and clean the filter afterward.
Metal Stains (Iron / Copper)
Typical signs: doesn’t fade with chlorine, but fades with Vitamin C / ascorbic acid.
- Iron stains: respond well to ascorbic acid reducers.
- Copper stains: often respond better to citric acid reducers.
- Use a metal reducer (ascorbic/citric based) and brush the affected areas.
- Run circulation at least 1 hour.
- Repeat if needed.
- After lifting the stain, add a metal sequestrant to keep metals suspended.
- Consider a skimmer metal eliminator pack to help prevent recurrence.
Rust Stains
Typical signs: reddish-brown and often localized (ladder area, screws, metal contact points).
- Fill a sock with ~½ cup dry acid (sodium bisulfate).
- Hold it directly over the stain (pole/weight helps).
- Check every 1–2 minutes.
- Remove immediately once the stain lifts to avoid discoloration.
Waterline Rings
Typical signs: brown/gray ring at the waterline from oils + organics.
- Add enzyme treatment to break down oils.
- Scrub waterline using a safe pool brush/eraser.
- Maintain filtration and skim regularly.
Mineral / Calcium Scale (White/Gray, Crusty)
Typical signs: chalky deposits or crust near/above waterline.
- Scrub with a 50/50 vinegar-water mix
- Baking soda + vinegar scrub
- Lime juice + salt scrub
Long-term fix: reduce scale conditions (high pH/high calcium) and keep water balanced.
What We Usually Recommend (Generic Guide)
Not sure what to buy? This is the general direction — we’ll fine-tune it in-store.
Organic
- Shock (as needed)
- Enzyme treatment
- Brush + filtration
Metals
- Metal reducer (ascorbic/citric)
- Metal sequestrant
- Metal eliminator pack (optional)
Scale
- Scale inhibitor
- Balance pH & calcium levels
- Brush/scrub affected areas
When to Call Us
Some stains need a pro to avoid permanent damage or recurring issues.
- Stains return quickly after treatment
- You suspect metals in well/fill water
- You see pitting/flaking or rough plaster damage
- You suspect a heater/metal component issue
- You’re not sure what’s vinyl-safe vs plaster-safe
Want us to identify it for you?
Bring a water sample in and we’ll help you confirm what’s happening and what to do next.
- Water sample (12–18" below surface, in a clean bottle)
- Pool type (vinyl / plaster), sanitizer type (chlorine / salt)
- Approx gallons (if known)
- Any recent chemicals added
- Tell us if you recently filled from well or municipal water
- Pictures! Bring Pictures! Did we say, bring pictures?