CHOOSING A CHEMICAL
The chemical you choose to use will have a major
effect on the performance of your pH system, as well as on the cost of maintaining
it. But which chemical to use is a matter of trade-offs. One of the most
important considerations is safety. Any chemical can be dangerous if it isn't
handled properly -- concentrated chemicals the more so. My caution to you is to not
lick you fingers of rub your eyes. And please, always wear safety glasses. The
chemical chosen, and its strength, will determine how thoroughly (and therefore how
effectively) the chemical mixes with your water and makes the pH change you desire.
Too weak a chemical will call for a larger and more expensive feed pump. Too strong
a chemical can result in plug flow and a system whose treated pH surges up and down.
If you are treating a domestic, or potable
water, your best bet is still an honest local water treatment professional who guarantees
his work. That may still lead you to a pH controller/pump system, but generally only
the most difficult of waters would call for that. You can do an inexpensive
preliminary check of your water by going to Jar
Testing Made Easy, where you can get an equipment kit and tester for your water.
If you are treating a process water or
wastewater, you might start by going to the table on Relative
pH Solution Strength. Which chemical you use will depend upon your particular
application and plumbing. Still, you can see that, for example, you would use forty
times less of a 50 % sodium hydroxide solution than you would of a 5 % soda ash
solution. The stronger solution would let you select a much smaller chemical pump
and lower your chemical expense, but it would probably increase your concern over the safe
handling of the chemical. And there are sidebars: A pure 50 % sodium hydroxide
freezes near 56oF, while a 25 % sodium hydroxide freezes around 33oF.
Will your chemical be stored in a heated environment? Or should you look for a
chemical vendor who offers a product that contains antifreeze? By the same token, a
concentrated sulfuric acid is thirty-six times stronger than acetic acid. Same
trade-offs, except that freezing is not as much of a concern.
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