Professional supply stores utilize either sodium thiosulphate or sodium hydroxymethane sulphonate to make waterbed conditioner. Both are reliable. To make your own, mix either chemical with distilled water according to directions. Most waterbed companies suggest treating a waterbed every six months. Mixing the chemicals more strongly won't help extend the time period for retreating. The chemicals break down in six months.
Some recipes call for using ordinary household bleach in your do-it-yourself formulas. Chlorine bleach corrodes vinyl, so bleach formulas can eat a hole in the mattress. Some unscrupulous waterbed dealers sell bleach formulas made from Clorox.
Some sellers of waterbed products sell devices to "burp" bubbles out of waterbeds caused by microbes and algae. These bubbles can be noticeably loud and the water, if left untreated, can grow green and smelly. A mattress kept clean inside and out will last at least seven years.
Sodium thiosulphate is available at pool supply stores. Sodium hydroxymethane sulphonate is available in aquarium stores or via the Internet. Breathing or touching these chemicals can cause liver damage even in small amounts.
It's possible for waterbed mattresses to develop foul odors when neglected for long periods of time. Waterbeds should be drained and refilled every two years. If the water smells, an owner can apply a "shock" treatment similar to those used in swimming pools that have microbe and mold overgrowth. Chemicals used in shock treatments are more toxic and harder to find than chemicals used in more subtle treatments.