Hydroponics Water: A Complete Guide & FAQ

If you’re thinking about growing plants in water for the first time, rather than soil, be it strawberries, tomatoes, or something else, you need to know all about hydroponic growing systems and how they work before you even try to get started.

In short, hydroponics is a method of growing fruits, vegetables, and other plants in self-contained systems that utilize water, light, nutrients, and a substrate other than soil.

That said, understanding what type of water is best for use in hydroponics is one of the most important aspects to begin your learning curve with.

Distilled water is the most preferred type of water for hydroponic systems due to its lack of harmful contaminants. Once diluted with tap water, it is the best option. Alternatively, tap water that has undergone reverse osmosis filtration is another great choice.

Hydroponics Basics

Light, water, carbon dioxide, and oxygen are necessary for growing things. Soil isn’t.

Hydroponic growing systems replace soil with another material that supports the plant’s roots, allowing plants to grow directly in water. 

Basic hydroponic growing methods include:

  • Water Culture: One of the most popular hydroponic growing methods; a medium holds the roots, the plant floats directly on the top of the water and nutrients, and a pump supplies oxygen into the water.
  • Wick System: The most basic hydroponic setup; plants grow in a tray on top of the water and a wick draws water and nutrients into the growing medium.
  • Ebb and Flow: A hydro method where a pump and timer are used to flood the growing medium with water and nutrients and then drain back into the reservoir.
  • Nutrient Film Technique: A very simple hydro-growing method; plants are placed in baskets with roots suspended above a constant flow of nutrients and water.
  • Drip Systems: Another of the most widely used types of hydroponic systems; a pump and timer connected to a tube or hose drip nutrients and water into the growing medium.
  • Aeroponic Systems: An advanced method for growing hydroponically; plants are suspended in the air as with NFT systems but rather than a constant flow of nutrients, the roots are misted every few minutes.

What Kind of Water Is Used in Hydroponics?

Water needs to be specially treated to remove harmful chemicals and contaminants before use in a hydroponics system. Distilled and purified water are the easiest to use as they have already been purged of chemicals, minerals, and bacteria. That said, tap water, filtered water, well water, and even rainwater can be used for hydroponic growing after it’s treated.

How To Treat Tap Water for Hydroponics

Treating water for use in a hydroponic growing system is rather simple:

  1. Place the tap water in direct sunlight for one to two days to remove chlorine via UV rays.
  2. Next, apply one tablet (good for up to 20 gallons) for removing chloramine. There are also tablets that remove both chloramine and chlorine at the same time, allowing you to skip step one. Additionally, running water through an active-carbon filter removes chloramine as well.
  3. If your tap water is hard water, a reverse osmosis filter needs to be used to remove the calcium and magnesium.
  4. Finally, run the water through a debris filter to remove any leftover debris in the water.

Now your tap water is properly treated and ready to be introduced to your hydroponic system.

Is Distilled Water Good for Hydroponics?

Distilled water is one of the best choices for hydroponics as it has already had all harmful contaminants removed. That means the only nutrients your plants receive are the ones you purposefully introduce to your water. But, you may want to add some treated tap water to create a healthy pH level.

Can Rain Water Be Used for Hydroponics?

Rainwater is absolutely ok to use in hydroponic systems. However, due to heavy metals in the air and contaminants collected from runoff surfaces, like gutters and roofs, rainwater needs to be treated before you use it in your growing system.

Is Well Water Safe for Hydroponics?

Well water is not a safe choice for use in hydroponics due to the large amount of contaminants found in it. Coming from deep within the ground, enormous amounts of contaminants leach into well water.

Can Purified Water Be Used for Hydroponics?

Purified is a great choice for use in hydroponic growing operations as it allows for complete control over what nutrients the plants absorb. But, it is far from necessary as long as you properly treat your water first.

What Is Reverse Osmosis Water?

Reverse osmosis water is created through a special filtering process that involves pushing the water through membranes to remove debris, minerals, molecules, and harmful contaminants. It is one of the very best types of water to use in hydroponics.

How To Make Nutrient Water for Hydroponics

Making nutrient water for hydroponics is much easier than it sounds:

  1. Purchase a micronutrient mix/water-soluble fertilizer and epsom salts.
  2. Read the instructions for mixing with water.
  3. Add the correct amount of fertilizer to the water (probably two teaspoons) and stir it well.
  4. Mix in a teaspoon of epsom salts for every one gallon of water.

That’s it! Now your water is loaded with the right sort, and amount, of nutrients for hydroponics. Just remember that you’ll need to add more nutrients every week to every week and a half and you’re good to go.

Correct pH Level for Hydroponics

Depending on what you are growing, the best pH level for Hydroponics is generally between 5.5 to 6.0 and 4.0 to 5.0. Vegetables prefer a higher pH (5.5 to 6.0), and berries require lower levels (4.0 to 5.0).

How To Test Hydroponic Water

Hydroponic water requires two types of testing; pH and EC. Both types of testing are most accurately measured with meters. To do so, power the meter on, stick the probes into the water, and read the display on the meter.

Alternatively, pH test strips can also be used to test hydroponic water also. Simply dip the strip into the water for a couple of seconds and pull it back out. The results will appear after approximately 10 seconds.

How To Adjust the pH Level of Hydroponic Water

Adjusting the pH level of the water in your hydro system is relatively easy, even if you don’t have a stock of professional supplies. 

If the pH level is high, all you need to do is add something containing alkaline, such as baking powder, to lower it.

On the other hand, when pH levels in your water test low, adding citrus raises it up. Lemon juice or white vinegar are a couple of the most common household items used for this purpose.

Water Pumps for Hydroponics

The purpose of water pumps in hydroponic growing systems is dual; to pump water and move nutrients.

Depending on the type of hydroponics that you’re working with, the details may vary a bit. For this reason, we discuss water pumps for hydroponics in further detail in the sections below.

Types of Water Pumps Commonly Used in Hydroponics

There are two types of water pumps that are most commonly used in hydroponic setups; submersible and inline.

  • Submersible water pumps: These pumps are directly placed into the water, are cooled by the water, and rely on hoses and fittings to move the water and nutrients through the rest of the system.
  • Inline water pumps. This style of pump is attached on the outside of the system, is cooled by the air, and transfers water and nutrients from inside the holding tank to the tray and growing medium.

Which Water Pump Is Best for the Home Hydroponics Gardener?

Submersible water pumps are generally considered the best, and easiest to use, for home hydroponics gardeners. This is due to the fact that home hydroponic systems tend to be smaller and require less power to move water.

Water Pump Timers – Do You Need One?

The water pump timer is a key component to many, but not all, hydroponic systems. 

For example, aeroponic, drip, and ebb and flow all heavily rely on timed water and nutrient movement. NFT systems can do with or without water pump timers.

On the flip side, water culture and wick systems don’t utilize water pumps at all. Therefore, a water pump timer is not part of the system either.

Is an Air Pump Necessary?

Air pumps aren’t necessary for hydroponics other than in deep water culture setups.

That said, air pumps assist in dissolving oxygen in the water as well as preventing disease and algae growth and can be used for hydroponics regardless of not being a requirement for the system to work properly.

How Often Should You Change Hydroponic Water?

The average home hydroponics system needs its water fully changed every two to three weeks like clockwork. In between full water changes, feel free to top off your water levels by adding small amounts of water every so often.

Keep in mind that sometimes you may need to change out your water supply early. For example, if your system begins growing abnormal amounts of algae, change the water immediately.

If not, the harmful bacterias from the algae may produce disease and infect your plants.

Likewise, when testing pH levels in your water, if an extreme unbalance is noted, changing the water right away is always the best course of action rather than trying to doctor up the pH levels by adding ingredients as mentioned in earlier sections of this article.

Additionally, when you are changing hydroponic water, make sure to wash out the tank and scrub it as well.

Avoid using chemical-based cleaners or soap and stick with elbow grease and/or plant-friendly cleaning solutions.

Can Hydroponic Water Be Recycled? | Disposing of Used Nutrient Water

The best way to safely dispose of used water from a hydroponic system is to recycle and/or reuse it.

This can be done by:

  1. Draining the used water into a bucket or container.
  2. Mixing equal amounts of tap water with the used water.
  3. Pouring the water down a drain in the bathroom or kitchen.
  4. Alternatively, using the mixture to water plants in self-contained pots with no drain holes.

Or, you can purify and dispose of it normally instead of recycling and reusing it. The best way to do so is:

  1. Using a reverse osmosis filtration system, UV disinfection system, or pasteurization equipment.
  2. Testing the water’s pH level, which needs to be between 6.5 and 8.5 before it is considered safe for disposal.
  3. Checking the EC level of the water, which should read as close to 0.0 as possible.
  4. Disposing of the now safe water however best suits you.

Water Temperature for Hydroponics

In all types of hydroponics, the correct water temperature is absolutely critical for successful operations and regular/healthy plant growth.

The water temperature in any hydroponic system should be monitored and maintained between 65F and 80F.

Temperatures higher, or lower, than the suggested 65F to 80F causes massive shock to plants, starting with the roots and their ability to intake the proper amount of nutrients and water.

Failure to quickly correct the situation results in dead plants.

Managing water temperature for hydroponics can be achieved through by:

  • Setting your system up in a shady area
  • Painting the tanks/reservoirs
  • Using a swamp cooler or chilling coil
  • Burying the tanks/reservoirs in the ground
  • Keeping the water levels topped off
  • Using larger tanks/reservoirs
  • Keeping the temperature outside of your system between 75F and 80F

Perhaps one of the most overlooked aspects of home hydroponics, maintaining the right water temperatures is an easy disaster to avoid if you are simply aware from the get-go and practice one or more of the above-mentioned tips.

Hydroponic Water Levels

The correct water level of hydroponics depends on the sort of system you’re using. The bottom line is that your system’s water should keep your plant’s roots wet, but the stems should always be dry.

The proper water level makes sure this is always the case.

In ebb and flow, water levels should be roughly two inches below the growing medium. That way the roots are never exposed to too much air.

On deep water culture setups, the correct water level is one inch or so below the net/pot. However, if the bottom of the plants is dry, the water needs to be slightly raised.

Likewise, if the plants’ bottoms are sloppy wet, the water needs to be lowered a bit.

NFT, aeroponics, wick, and drip systems don’t have a suggested water level due to the difference in how they utilize and deliver water.

Can You Overwater in Hydroponics?

Overwatering can and does occur in hydroponics. Typically, overwatering happens when:

  • The water level is too high and oversaturation of the growing medium in NFT and deep water culture system
  • The pots in drip systems don’t have good enough drainage and they become filled with water.
  • Growing mediums in various systems become flooded with too much water or are flooded too often.
  • Water pump or timer malfunctions occur.

A Final Word About Water Use in Hydroponics

Successful water use in hydroponics requires specially treated water, correctly mixed nutrients, well-balanced pH and EC levels, in addition to proper water levels and temperatures, and more.

Trying to set up and run a hydroponics system without understanding proper water use is like trying to cook burgers on an old-fashioned grill without understanding anything charcoal; it’s bound to end in disaster.

If you’re unsure of something, revisit this article as many times as necessary, or seek additional resources.