Expert: Henry Boyter - 3/20/2002

Question
I have a waterbed and have to add a solution every year to keep the water from going off.  This solution is expensiver and the ingrediants are listed as Benzalkoniun Chloride Solution 35% and Water 65%.  Can I buy this Benzalkoniun Chloride from a chemist or is there another more common household substance I can use.
Cheers
Pete

Answer
Keep buying the commercial product.  The chemical ingredient listed is a family not a specific chemical.  Deformulating their mixture would be expensive.  Even if it was a single chemical, the cost to buy the pure chemical would be very expensive and you may have to buy so much that it would last 10000 years.  You also may not be able to buy the chemical pure, since it is a pesticide/herbicide (that's why it keeps the growth down).  There is probably only 1-2% active ingredient in the product and it may have other inactive (but important) ingredients not listed on the bottle.

The same is true with pool chemicals.  Formulating your own is more expensive, even for a chemist due to the bulk amounts you have to buy and the restrictions on buying them.
It is similar to gasoline, no one buys crude oil and distills their own gasoline.  Even with profit, it is cheaper to buy commercial versions in almost all cases and mixing your own can be very dangerous.