Mineral buildup (scale) is the #1 maintenance issue for evaporative coolers, especially in areas with hard water. Here's how to prevent and manage it:
Understanding the problem:
When water evaporates, minerals stay behind and concentrate in the remaining water. These minerals (primarily calcium and magnesium) deposit on pads, pumps, water lines, and the reservoir as white, crusite scale. This reduces efficiency, clogs components, and shortens equipment life.
Prevention strategies:
1. Regular water changes
- Drain and refill the reservoir weekly
- Never let water sit stagnant for days
- This is the simplest and most effective prevention method
2. Install a bleed-off valve
- Continuously drains a small amount of water (1-3 gallons/hour)
- Fresh water constantly dilutes mineral concentration
- Most effective for very hard water areas
- Increases water usage but significantly extends pad and pump life
3. Use water treatment
- Add cooler treatment tablets or liquid monthly
- Products like "Swamp Cooler Treatment" reduce mineral adhesion
- Some contain algaecides to prevent biological growth
- Follow package directions—more isn't better
4. Clean the reservoir regularly
- Scrub the pan/reservoir monthly during cooling season
- Remove accumulated scale with a stiff brush
- For heavy buildup, use white vinegar or CLR (calcium-lime-rust remover)
5. Consider water softening
- Whole-house water softeners reduce mineral content
- Inline filters specifically for coolers are available
- Cost-effective for homes with extremely hard water
Removing existing scale:
- Soak affected parts in white vinegar for several hours
- Use commercial descaling products
- For pumps and lines, run diluted vinegar through the system
- Heavily scaled pads should be replaced rather than cleaned
