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Step by Step pH Adjustment

Adjusting the pH of irrigation water is critical to optimizing a plant’s utilization of nutrients.

Thankfully, adjusting the pH of your water is a fairly easy process. Dilution Solutions is here to break it down for you. For most crops, adjusting the pH usually means a pH range of 5.5 to 6.5. The most effective way to adjust pH is by injecting acid into the water system.

Here’s what you’ll need to set up an acid injection system:

The acid. Many types can be used including, sulfuric, phosphoric, nitric, etc. Use the type of acid recommended by your fertilizer supplier or university specialist.

pH meter. While it is possible to check pH with paper strips, investing in a good digital meter will be more accurate. It’s a tool you’ll repeatedly use during the crop’s growing cycle to check the pH of the irrigation water. [Make sure to periodically calibrate your pH meter according to the manufacturer’s recommendation.]

10ml plastic syringe.  You can pick these up at any drug store.

10-gallon container.  [Plastic container, preferably polyethylene] Using a container that holds 10 gallons makes the math easier…always a good idea!

1. Begin by filling your container with 10 gallons of your source water.

2. Next, measure the pH of the water. [For our example, let’s say the pH reading of the source water is 7. In this example, our target pH is 5.5.]

3. Fill the syringe with the acid and add several drops to the 10-gallon container. Stir to mix thoroughly and test the pH again. Continue to add acid a couple of drops at a time, stir and test. Go slow; the pH can change suddenly.

4. When you reach the desired pH level, note on the syringe the number of ml of acid you used. [In this example, let’s say the amount used was 16 ml.] Since this amount of acid is needed to adjust 10 gallons, we can divide by 10 to get the amount necessary to adjust one gallon of irrigation water.  16 ml per 10 gallons = 1.6 ml per 1 gallon

5. We can now choose the best type of injection equipment to place the acid into the irrigation system.

 

One of the easiest systems to use pairs an electric Etatron pump with a water meter. The Etatron receives a signal from the water meter and injects a predetermined amount of concentrated acid directly into the waterline. Each stroke of the Etatron injects .15 ml, so in our example, the Etatron would be set to deliver 10 strokes per gallon of water passing through the system.

Proportional Dosatron pumps can also be used to modify irrigation water pH. A water meter is not needed for this injector as water passing through the unit drives a piston pulling acid from a stock tank. This type of injection system does require diluting the acid with water for the stock tank.

Using the chart on this page as a reference, select a dilution rate located in the far right column. You can choose any dilution rate for the injector you wish to use. It’s typically best to use a rate in the middle as this gives more range to make adjustments later.

In the case, we will choose 1:250 ratio. Reading across to the left-hand column, we see this will inject 15 ml of stock solution for each gallon of water.

15ml / 1.6 ml acid per gallon = 9.375, which we round up to 10

In our example, we are using a 25-gallon stock tank.

25 gal stock tank/ 10 = 2.5 gallons of acid.

25 gallons -2.5 gallons = 23.5 gallons

We would mix 23.5 gallons of water with 2.5 gallons of acid for our stock solution.

We can now go downstream of the acid and fertilizer injectors and take pH samples of the irrigation water. By slightly adjusting the Etatron or Dosatron units’ injection rate up or down, we can hit our target pH of 5.5.

Please note: This calculator and information provided in this blog is for informational and educational purposes only and should be verified independently prior to its use. User of these calculators is responsible for verifying the calculations. Dilution Solutions, nor its employees, assume any legal liability or responsibility for their accuracy, and any consequential damages or faults that may arise from the use of the calculators or information contained in this blog.

For questions, or to learn more about how Dilution Solutions can provide you with the tools you need for simple pH adjustment, please contact Jose Rodriguez at 1-800-451-6628 or e-mail at [email protected]