The Ultimate Beginners Guide To pH For Hydroponics

Thomas Angas by Thomas Angas | Last Updated: April 13, 2020

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When you first get into hydroponics, there are certain new concepts that you might have to get your head around like the different systems, nutrients and of course pH. I’ll be honest, I was never much of a chemist at school and I really struggled to understand the whole pH thing.

Once I became familiar with the basic concepts below it all suddenly clicked into place and understanding pH for hydroponics wasn’t a huge challenge anymore. In this beginners guide, you’re going to learn about pH, why it’s important for hydroponics, how to test pH levels and when you should tet.

Let’s get started!

a picture of a ph meter in use

What is pH?

pH stands for “potential of hydrogen” and is a numeric scale to display the hydrogen ion concentration of a solution. The hydrogen ions are made up of two parts – positive (hydrogen – H+) ions and negative (hydroxyl – OH-) ions. More acidic solutions contain more positive ions while an alkaline/basic solution will contain more negative ions.

That’s enough science for today – everything from now on will be much simpler.

On the pH scale, water sits right in the middle and is classed as pH neutral and given a rating of 7. All solutions that are more acidic than water are given a lower score and everything more alkaline are given a higher score. For example, vinegar would be lower down on the scale compared to water while milk would be higher.

Why is pH Important For Hydroponics?

Within hydroponics gardening, the pH level of your system is one of those numbers that should always be at the front of your mind. Understanding the pH level of your hydroponics system lets you know how soluble the nutrients in the water are which determines how your plants are able to take up nutrients.

What is the ideal pH for Hydroponic plants?

Okay, so this is one of the concepts that I initially found difficult to understand so have made it extremely non-technical for other beginners…

Nutrient availability referees to the pH level of your water in which different nutrients can be absorbed. Most of the main macronutrients are most easily absorbed at a pH level of between 6.5 and 7.5 while micro-nutrients, those nutrients needed in smaller quantities, often prefer a slightly more acidic pH of between 5.5 and 6.5.

The more advanced your system the smaller the pH range within your system and the better your plants will grow.

pH Testing

So now you know why pH is important for hydroponics it’s time to look at how you test pH levels.

The first thing to know is that pH testing is something that should be done regularly – this is known as the testing schedule. For beginners this might be once a day, however, for commercial growers, this might be a constant monitoring process.

As you might have seen in our guide to the best pH meters for hydroponics, There are a number of tools available to help you test the pH of your system.

Litmus Test Strips

Litmus test strips are the cheapest and easiest pH testing solution to use. You simply dip the the strip into your solution take it out and watch it change color. From there you compare the color of the testing strip to the color chart provided with the testing strips and you’ll then have an idea of what the pH level of your water is.

The obvious downside here is that you never have an exact pH level – only an approximate level based on visually matching strip to chart.

Liquid Test

Liquid pH testing is a step up from litmus test strips and more accurate. To use, you take a small sample from your liquid solution and add a few drops of dye into the solution. It’ll then change color and you’ll be able to cross-reference this against the color chart. Where this differs from litmus tests is that the colors are much more pronounced so you’ll have a much better idea.

Digital pH Meter

While digital pH meters were once seen as luxury items only used by commercial growers, they’re now becoming more commonly used by domestic growers partly due to prices coming down making them a more affordable option. While the exact usage instructions will differ between units, essentially you put the probes into your solution, press a button and within seconds you’re given a very exact level. The only downside to digital pH meters is that they do need to be regularly calibrated but the process doesn’t take long – it more something to keep in mind.

When Should You Check pH Levels?

The final piece of the puzzle is when should you check pH levels? Typically this should be done after you’ve mixed your hydroponic nutrients, added them to the water and have given them sufficient time to cycle through your system.

The Bottom Line

So there you have it, our ultimate beginners guide to pH for hydroponics. Hopefully this hasn’t been too technical and has cleared up any questions you might have about pH levels in your system.

Thomas Angas, the founder of Authority Gardening lives with his wife and two darling pups. He spends his free time writing, hiking and learning how to become a better gardener. He launched Authority Gardening in 2017 to help people all over the world their gardens grow.