We should all value safety over profit however the desire to save or make money can mist our judgement.
Several chemicals used in the sanitisation of swimming pools and hot tubs are dangerous, corrosive and explosive in the right conditions.
Packaging is clearly marked with the dangerous and handling advisories. Chemicals transported from the manufacturer should arrive in vehicles bearing content warnings and packages accompanied with appropriate hazard paperwork.
Most swimming pool and hot tub chemicals are not allowed to be shipped using Royal Mail, Parcelforce or many other couriers. It only takes a collision of a vehicle carrying a mixed load of oxidisers like these chemicals to result in a serious incident.
Think twice about buying split lots of chemicals on ebay. Check the shipping method. make sure your chemicals carry all the necessary cautionary information.
Check the chemicals are a reputable brand. If you are placing your children in water containing these chemicals do you know where they are made? who is the manufacturer, is there adequate quality control over each batch or year of chemical. If the seller is not offering despatch using an authorised courier for such chemicals or offering personal delivery try and collect yourself.