Pool Drain & Refill Calculator (Calcium Hardness)
Calcium Hardness does not evaporate or naturally lower. Calculate exactly how many gallons you must drain and refill with fresh water to hit your target Hardness level.
Technical Comparison
| Method | Cost | Time Required | Risk |
|---|---|---|---|
| Standard Drain & Refill | Low (Water Bill) | 1-3 Days | Medium (Liner float/Shrinkage) |
| Reverse Osmosis (RO) Truck | High ($500+) | 1 Day | Zero Risk |
| Tarp Exchange Method | Low | 1 Day | Low Risk |
Frequently Asked Questions
Can I use chemicals to lower Calcium Hardness?
No. Unlike pH or Alkalinity, there is no practical chemical you can add to a pool that permanently removes Calcium. Reverse Osmosis (RO) filtration or partial draining are the only solutions.
How far should I drain my pool?
Never drain a plaster pool empty or an above-ground pool below 1 foot. If you need to replace 80% of your water, do it in multiple small phases or use the 'Tarp Method' to prevent structural collapse.
Get the Complete DIY Pool Maintenance Guide
Free PDF checklist including seasonal schedules, chemical balancing secrets, and maintenance tips.