There are actually three things to consider when determining the proper pH for your hydroponic gardening:
1. The nutrient reservoir
2. The water you are using
3. Your growing medium
Ignore any of these three things and you will diminish the quality and quantity of your crop. These three things form a circle that when kept in balance holds the key to successful hydroponic vegetable gardening.
Misconceptions about water
One of the major culprits that can affect your success is water. That’s because most water is alkaline.
Actually, water is seldom just water. It contains a lot of stuff such as calcium, magnesium, sodium and potassium. These come in forms of carbonates and bicarbonates with the bicarbonates being the worst offender.
Alkalinity in your water can cause your growing medium pH to zoom faster than a rocket and add all sorts of stability problems to your reservoir. Remember, pH levels should be kept between 5.8 and 6.3 for best results in hydroponic growing. Allowing it to drift too far above or below these levels will reduce the quality and quantity of your harvest. It can even kill your plants.
Don’t rely on water softeners
Water softeners only displace calcium and magnesium ions. That leaves behind both carbonates and bicarbonates. That does nothing to change the alkalinity of the water.
Water softeners also add a lot of unwanted sodium to your water. So by trying to fix one problem, you create another which can greatly decrease your yields.
Also remember, if you’re using well water, it’s almost guaranteed to have alkalinity problems. Even city water is often of poor quality. Invest in a reverse osmosis system. They are relatively inexpensive and will take the alkalinity out of your water along with other impurities.
What’s the best tool for measuring pH?
Use a meter that measures EC (Electrical Conductivity). This type of meter was made specifically for measuring nutrient solutions. Taking pH readings during the light cycle will give you a different result than when you take pH readings at night. The reason is during dark periods; both microbes and the plants are resting and giving off alkaline molecules. This tends to make the pH go up and during the day, the plant and microbes are active and tend to give off acid molecules. This makes the pH go down.
The importance of your medium
A plant root system is actually a pH excreting machine. It manufactures and pumps hydrogen ions (pH down) or hydroxide ions (pH up) directly into your growing medium. This can directly change the pH of the growing medium.
To assure the greatest success with your hydroponic vegetable gardening , your plants must have an acidic pH growing medium.
And, of course, the water, the growing medium and the nutrients should all be working in perfect harmony. But it’s the roots in the growing medium that drive the pH chemical reactions.
This is very important because the pH in the root zone is going to determine the availability of nutrients to the plant. And this, in turn, has a direct effect on the quality of your crop. So you should check your growing medium pH once a week.
It’s the ‘little guys’ that do a lot of the work
Beneficial microbes are bacteria that colonize within the growing medium and on the root system that help to create outstanding harvests. These bacteria help to keep your pH stable and your growing medium more acidic.
Some beneficial microbes will develop into your medium naturally. But the best and most efficient way of making certain of your plants have the beneficial microbes they need to grow and remain healthy is by introducing them in specially formulated hydroponic products.
However, this is one area where you don’t want to go cheap. The products you choose should contain active microbes that are ready to multiply and colonize the root systems.
Also, look for products that have a balanced microbial interaction with each other. This helps the growing medium hold its pH. And buying products from a company that breeds and produces its own beneficial microbes in house will help assure that you’re getting healthy active bacteria.