Never store these together
Chlorine products and acid. Mixing them, even by a spill or a leaking jug on a shelf above another, releases chlorine gas.
Different chlorine types. Cal hypo and trichlor together are a genuine fire risk — this combination has caused garage fires, not theoretical ones.
Oxidizers and anything flammable. Keep chlorine away from gasoline, oil rags, fertilizer, and the lawnmower.
The rule that covers all of it: separate containers, separate shelves, acid low and never above anything else, everything sealed and labeled.
Texas heat destroys liquid chlorine
Liquid chlorine loses strength steadily, and it loses it much faster hot and in the light. A jug that sat on a hot store pallet or in your garage for a month is substantially weaker than the label claims.
Buy it fresh, buy what you will use, and store it cool and dark. If you find yourself adding more and more with no result, the product may be the problem rather than the pool.
Cal hypo and dichlor keep better but hate moisture. A humid garage will cake and degrade them.
Handling basics people skip
Always add chemical to water, never water to chemical.
Never pre-mix two chemicals in a bucket, and never reuse a bucket between products.
Add one thing, let it circulate, then add the next. Dumping acid and chlorine in the same skimmer within minutes is the same mistake as mixing them on a shelf.
Eye protection and gloves. Splash injuries from acid are the most common home pool injury that is not a slip.
The honest recommendation
The safest amount of pool chemical to store at home is a small amount, or none. Part of what full service buys is that the dangerous inventory lives on a properly equipped truck instead of next to your car.
