Growers often ask why their plants are unhealthy even though they use the right nutrients, feeding cycles, grow lights, adjust ideal temperatures and provide the right conditions. This is because their pH and PPM levels are off, which makes their plants difficult to consume. Your water’s pH indicates whether it is too acidic or too alkaline, based on the number of hydrogen ions it contains. Mineral and soluble matter concentrations in your watering solution are indicated by parts per million (PPM). An accurate pH and PPM level is the backbone of hydroponic gardening and will mean the difference between a successful harvest and a huge waste of time and money.
Understanding pH Levels
By creating a pH level that is optimal for plant nutrient absorption, you will increase your harvest.
In hydroponic systems, you use nutrient-rich water filled with elements that are helpful to plants. Those same elements can harm your hydroponic plants if they cannot be broken down properly. You need to understand pH levels because they determine the quality of helpful bacteria in your water, which improves the metabolism of your plants. Exactly how?
- Heavy metals like iron and aluminum can become toxic to plants when the pH is too low.
- Expect stunted growth of your plants due to nutrient lockout if the pH is too high.
Your water’s acidity is the reason for the change in properties. You want your plants to be a little acidic so they don’t break down, but too much acidity can make them toxic, and you should remember that. You want the perfect level of acidity in your neutral water to be around 5.5- 6.0.
Most nutrients in a hydroponic fertilizer are dissolved into ions that your plants can absorb. Thus, ion concentration changes your nutrient’s electrical conductivity. Digital meters measure the electrical conductivity of water, which is the EC.
What is TDS?
As growers, we generally aren’t interested in the EC because the EC doesn’t matter to the plants. What matters is how much of the various hydroponic nutrients are in the solution. My point is that EC is not important to the plant since many ions will affect it in different ways. For example, sodium chloride (table salt) in a liter of soft water will have a different EC than potassium chloride in a liter of water. In addition, some organic nutrients, such as green sand, blood/bone meal, and fish emulsion, produce very little change in EC. Still, when broken down by beneficial bacteria, they yield useful nutrients.
American TDS meters attempt to reduce the problem to some extent by changing the EC to PPM. To convert EC to PPM, a constant (either .5 or .7) must be multiplied by the EC in micro siemens. As a side note, the EC reading on most meters is in milliSiemens, so remember that.
Checking PPM Levels
The PPM of your nutrient solution refers to its particulate concentration. Hydroponic water preparation involves considering both natural elements found in your nutrients and minerals found in the water. Your responsibility is to ensure your watering solution has the right amount of PPM so that your plants aren’t being under or overfed. Although it’s an easy concept to understand on the surface, it becomes more complicated when you have to adjust nutrient levels inside a grow room or grow tent. The pH of the soil greatly affects PPM levels because even if you have the correct reading, some of the particles- and their concentrations- may hurt your plants.
Imagine that you need 700 PPMs for your plants. After mixing the solution, the PPM reading is 700, but your pH is around 4.5. In other words, a majority of the available food for your plants contains heavy metals. These metals will quickly poison the plants. You should adjust your pH level to ensure you do not poison your plants. But won’t adding particles to the feeding solution throw off the PPM levels? It can, which is why both PPM and pH levels can be tricky to change: you usually have to adjust both simultaneously, which can be easy or difficult depending on the water and fertilizers you use.
Adjusting pH Levels
When it comes to feeding plants, there are two ways of looking at it: homemade or store-bought. Likewise, balancing your pH can be accomplished by buying a pH buffer or by using ingredients found around your house or in the grocery store – but each has its advantages and disadvantages.
Homemade pH Buffers
Pros: When the pH levels in your water are above neutral, you can use white vinegar or citric acid to help reduce it. Baking soda can be added to your hydroponic nutrient solutions when your pH levels fall too low. If you do this, you will spend less than if you purchased a buffering solution.
Cons: In the long run, these solutions don’t work. Adding a little lemon juice every other day, then a little baking soda to level things out, will seem like a daily chore. It has also been reported that hydroponic growers have used these ingredients and experienced severe spikes in pH, which can halt plant growth if not handled properly.
Premade pH Buffers
Pros: In hydroponic growing, pH buffers are usually called pH Up & pH Down. Citric acid or white vinegar mixes are much more difficult to use. The pH levels in your water will remain balanced much longer than without them. They raise and lower the pH levels of your regular water.
Cons: Easy usually means more expensive, as we’ve always said. Although you won’t spend an arm and a leg on these solutions, they aren’t something you can make at home and cost money.
Ensure to check your pH levels because no matter how much training you do, if your pH levels are left unchecked, they will halt your plant’s growth.
Adjusting PPM Levels
You should first make sure that your distilled water is ready for the plants before adjusting the PPM levels. So you’ll need to adjust your base water’s PPM before you start feeding it to your plants. You will be adding more particles to your watering solution any time you add something to it, so be aware of your PPM level at all times.
- You can use a reverse osmosis machine or an active carbon filter to clean water that contains too many particles. However, most growers agree that clean tap water has beneficial minerals (such as calcium and magnesium) that plants need.
- Plants need more nutrition during vegging, and afterward, so water filtration isn’t necessary. Because of this, we suggest using a basic water filter when readings of low PPMs are needed at the beginning of a plant’s life.
- The quick fix for high PPM levels is to add a bit of freshwater with a high pH level and watch them drop. If things get a little out of hand in your reservoir water, filtered water can help.
- Low readings indicate that your plants need to be fed. PPMs and pHs will be in balance when you add nutrients to your hydroponic solution. Happy and healthy plants will then occur when these are at their best.
There is no better time than right now to begin keeping an eye on your plant’s PPM and pH levels. Just remember that these readings need constant adjustment. It’s important to remember when growing indoors that you control all factors affecting the plant’s environment. Things can go wrong in your grow room even if all other factors are perfect, like light, water temperature, and humidity.