We all know there are many advantages to hydroponic gardening over traditional, land-based farming. One advantage is that drastically less water is needed. It is one of the main reasons many of us choose to garden hydroponically and why many nations with limited water resources and harsh climates are turning to hydroponics as their preferred method of farming. Even with these advantages, there are many ways we can increase water savings with our hydroponic systems and further the green goals of all hydroponic gardeners.

Eliminate Excess Heat

Heat is one of the biggest enemies of water conservation when gardening with hydroponics. Too much heat in the growroom will cause water to evaporate and plants to drink more than they would in cooler rooms. There are several ways to effectively eliminate heat in the growroom:

  • Gardening in the basement rather than other parts of your home can help keep your reservoir and grow space cooler.
  • Venting your room frequently with a powerful inline fan can help maintain the cooler temperature your plants thrive on. Using air-cooled reflectors are an even more direct way of removing the large amount of heat produced by HID grow bulbs. Or you can grow with LED lamps, which run cooler than HID lighting systems.
  • Reservoir chillers are another way to keep your reservoir cool and prevent evaporation. Reservoir chillers are submersible refrigeration units that keep your nutrient solution at a temperature ideal for plant growth. Preventing evaporation will conserve water and prevent the nutrient solution from becoming too concentrated.
  • Keeping your reservoir covered will also help prevent evaporation and keep algae growth down, eliminating the need to empty and change your reservoir from the buildup of algae and reservoir sludge. Some reservoirs come with lids or you can use black and white plastic over top to reflect light away while preventing evaporation.

Reservoir Water Changes

Now that you have eliminated the excess heat in your growroom, it is time to focus on another way water gets wasted in the growroom—reservoirs getting changed out too often. The general rule of thumb for dumping the water and replacing the nutrient solution in your reservoir is every five to seven days. Nutrients are consumed by the plants and need replacing within that time frame.

There are numerous reasons reservoirs get changed sooner than necessary. One reason is simply the over-eagerness of beginner gardeners who are afraid of nutrient deficiencies/toxicities and are not equipped with an EC pen. Nutrient levels in your reservoir drop gradually as they are consumed by your plants. If left too long, plants can develop deficiencies, causing growth to become stunted. The opposite can happen as nutrient levels build up when your grow space is too warm and water evaporates from your reservoir. Having an EC, TDS or PPM pen to measure your nutrient levels is essential. This way if levels are too low they can be topped up for a short period of time. If levels are too high, extra water can be added to lower the nutrient concentration and prevent nutrient toxicities.

Another reason people empty their reservoirs sooner than the typical five to seven days is that there is a buildup of oxygen-robbing and pump and tube-clogging algae and reservoir scum and it needs to be cleaned out. This buildup can be prevented by keeping light from entering your reservoir, circulating the water with a pump, using multiple air stones to oxygenate your solution and adding hydrogen peroxide periodically.

Water Conservation

Now that you have eliminated the reasons why you might have to replace your nutrient solution more frequently than normal, there are easy ways to conserve water when you do have to empty your reservoir. Instead of simply pumping the old reservoir solution down the drain, why not use it to water your lawn, your outdoor vegetable and flower gardens, or your houseplants? The few residual nutrients will only benefit your plants and you can save gallons and gallons of water each week.

Water conservation is an issue that affects us all. As global populations continue to rise and urban environments become increasingly crowded, the issue of how to ensure the world’s water supplies are not depleted will continue to draw attention. We can all do our part, especially hydroponic gardeners, if we follow a few simple techniques that will help us use as little water as possible in a responsible way.