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What is Pool Cancer?
- Feb 16
- 2 min read
Updated: Feb 18
Signs, Causes & How to Fix Rust Spots in Pool Plaster
If you’re noticing rust spots, raised bumps, or calcium nodules in your pool plaster that keep coming back, you may be dealing with what we call pool cancer.
While “pool cancer” isn’t a technical industry term, it describes a serious issue: moisture intrusion behind your pool’s plaster that leads to rebar corrosion and structural damage.
Let’s break it down.
What Causes Pool Cancer?
Pool cancer begins when water penetrates small cracks or aging plaster and reaches the steel rebar inside your pool shell.
When rebar rusts, it expands — sometimes up to 7 times its original size. That expansion creates pressure behind the plaster surface, which causes:
Raised bumps in pool plaster
Rust-colored stains
Flaking or cracking areas
Recurring calcium nodules
Think of it like rust forming under car paint.Or like a cavity forming behind a tooth.
It starts small… but spreads if left untreated.
How to Tell If Your Pool Has Rebar Corrosion
You may have underlying pool structural damage if:
The same bump or rough spot keeps returning
You see rust stains bleeding through plaster
Calcium nodules come back after being scraped off
Small cracks continue expanding
If a repair doesn’t last, the issue likely isn’t cosmetic — it’s structural.
What Most Homeowners Do Wrong
Many pool owners unintentionally make the problem worse by:
Chipping off bumps without addressing the source
Acid washing repeatedly
Patching only the surface
Ignoring it because it “doesn’t look that bad”
These are temporary fixes.
It’s like taking pain medication instead of treating the actual injury. The symptoms may fade, but the damage continues underneath.
How to Properly Repair Pool Cancer
True pool cancer repair requires:
Opening the affected area
Removing or treating corroded rebar
Sealing the structure properly
Restoring the plaster correctly
Surface patches alone will not stop the corrosion process.
Early detection can prevent larger structural repairs and extend the life of your pool.
Concerned About Rust Spots or Recurring Calcium Buildup?
If you’re seeing rust stains in your pool plaster or bumps that won’t go away, it’s best to have it professionally evaluated.
Catching pool cancer early can save thousands in long-term repairs.
Contact Live Oak Studio today to schedule an inspection and protect your pool investment.
