Brown or red-brown
Recurring rust, iron, or corrosion-linked spots usually need source-water or metal treatment, not acid first.
Color/source
Color, source, and first move
Use the matrix to match the stain color and refill history to the safest next step.
White or chalky
Hard crust and rough white buildup point toward scale or tile-line cleanup before deeper stain work.
Gray, tan, or smeary
Organic staining and residue should be sorted before any aggressive treatment order starts.
Surface-safe correction
Use the stain atlas and compatibility matrix before acid-washing or brushing across mixed finishes.
Identify the stain before you treat it
Organics, scale, and metals do not get the same fix
Best when
- Organics, scale, and metals do not get the same fix
Check before you start
- Free Chlorine
- pH
- Calcium Hardness
Stop if
- Do not acid wash simply because a stain is visible.
Start here
Bad stain work often comes from using acid, chlorine, or abrasion before knowing what the mark actually is.
Skip this
- ✕Do not acid wash as a first response
- ✕Do not SLAM metal staining as if it were algae
Check these first
Free Chlorine / pH / Calcium Hardness
1
Note color and location
Start with where the mark is, what color it is, and whether it is on the surface or in the water.
2
Compare against chlorine history and refill history
The recent chemistry and fill-water story usually narrows the category.
3
Separate scale from metal from organics
Use behavior and history before choosing acid, chlorine, sequestrant, or abrasion.
4
Test a small area before larger treatment
Surface type changes how aggressive you can be.
Warnings
- Do not acid wash simply because a stain is visible.
5
Escalate when the source is unclear
A stain that keeps returning usually means the source is still active.
Resources (2)
Photo-Driven Stain Identification Helper
Use the photo helper when you want a visual first-pass before choosing a stain treatment.
Source water and refill water
Use the source-water guide when the stain keeps returning after refills or top-offs.
Educational guidance only. Verify labels, manuals, local code, and site conditions before acting. Stop for electrical, gas, structural, drain, drowning, injury, emergency, or chemical-mixing risk.