Furrow Pump, Inc.

P.O. Box 1849

8525 SW St. Helens Dr.

Wilsonville, OR 97070

Phone: (800) 937-3666

FAX: (800) 377-9960

www.furrowpump.com

While my original suggestion regarding jar testing was to size and select a chlorinator, the concept applies equally well when pH adjustment for a water or wastewater sample is required. The same equipment kit is used, changing only the tester and sample chemical. Incidentally, doing several tests (at least three) will establish an average test result more reliable than from a single test. The formulas given in the How to Size a Chlorine Feed Pump section allow for feeding different concentrations of sodium hypochlorite. If your concern is pH adjustment, and it is not practical to test with the actual chemical solution you plan to use, you can use the sample solutions suggested below and then refer to the Relative pH Solution Strength table (Table 2) to determine the Correction Factor multiplier necessary for your application.

For chlorination, it is common to use a 5.25 % bleach solution of sodium hypochlorite. Some customers prefer to use this solution directly, without dilution. Some prefer to dilute this solution with water (preferably softened water), for ease in handling and longer solution life. Others, with greater flow volumes, will want to use commercial strength sodium hypochlorite at a 12.5 % concentration. For jar testing, you can buy a quart of the 5 % bleach at a grocery store. If possible, try to find a bleach with a minimum of additives (phosphates, perfume, etc.) to do the testing with – a generic brand might be best. You can tell by checking the label.

For pH adjustment, you may need to take the pH either up or down, according to your particular application. Domestic water treatment often requires the pH to be raised, most commonly by soda ash (sodium carbonate), since it is comparatively safe to handle. Sometimes a weak solution of sodium hydroxide is used. If so, both the sodium carbonate and sodium hydroxide are typically made up at a 5 % concentration by weight with water. Industrial applications can call for a 25 % or 50 % solution of sodium hydroxide. For our purposes, however, we can test with sodium bicarbonate, or baking soda, and get a relative measure of the amount of caustic solution needed to raise the pH as much as necessary. To do that, you can prepare a 5 % solution by weight in water of the baking soda. By the way, go out and buy a new box to work with – pulling an old one out of the refrigerator may give you marginal results.

When the sample water’s pH needs to be lowered, there are a number of different acids that can be used. Household applications might call for a relatively weak acetic acid (white vinegar). Industrial jobs could require a strong muriatic or hydrochloric acid, or even sulfuric acid. Your local grocery store will have a quart of white vinegar, which is typically a 5 % solution of acetic acid, and quite adequate for jar testing. You’ll use more for your tests than you would with a strong acid, but the results will get you into the right ballpark as far as pump sizing goes.

NOTE: Any chemical, even those of a household variety, can be dangerous. The most vulnerable part of your body is your eyes. Please wear safety glasses and use care when doing jar testing.

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