Shock calculator
How to Shock a 15,000 gallon Pool with Cal-Hypo
Updated 2026-05-22
Use this dose for a 15,000 gallon residential pool with Cal-Hypo (calcium hypochlorite, 65%). Add at dusk so sunlight does not burn off the chlorine before it can do its work.
Routine maintenance
0.7 lb
Raises free chlorine by about 5 ppm.
Algae bloom
1.7 lb
2 to 3 times routine for visible algae.
Procedure
- Pre-dissolve granular shock in a 5 gallon bucket of pool water if your pool has a vinyl liner or sun-bleached floor.
- Pour slowly along the deep end with the pump running.
- Brush every surface, especially walls and steps where algae attaches.
- Run the pump 8 hours minimum, ideally overnight.
- Re-test free chlorine in the morning. Aim for 3 ppm or below before swimming.
Swim wait
8 hours, or until free chlorine drops back to 3 ppm.
Notes for this chemical
- Cal-Hypo raises calcium hardness slightly over time.
- Pre-dissolve granules in a bucket on vinyl liner pools.
- Cal-Hypo lowers pH temporarily, then settles.
Not sure if you need to shock?
Scan your test strip with PoolSense first. The app tells you exactly when shock is the right action, and how much.
Get PoolSense