Tap Water and its Impact on Hydroponic Nutrients and Supplements
Nutrients and supplements are added to water, which they mix with and change. However, tap water and the various elements found in it also have an effect on nutrients and supplements. There’s no point in feeding your garden expensive nutrients if the stuff in your tap water is keeping the plants from absorbing them.
Water is the basis of any hydroponics set-up. Nutrients and supplements are added to the water, which they mix with and change. Water and the various elements found in it also have an effect on nutrients and supplements—to put it simply, nutrients change water and water changes nutrients.
Chlorine and Chloramines
The most common issue regarding tap water and hydroponics is chlorine. Many growers don’t realize that chlorine is a micronutrient required by plants. The quantity they need is extremely minimal, though, so you do not ever need to add any.
Most growers add chlorine without realizing it, since it is already in tap water—this is a rookie mistake. Because plants can absorb this micronutrient, they take in far too much from unfiltered tap water. The result is diminished growth.
Root health is also disturbed by chlorine; beneficial bacteria and fungi are quickly killed off by this bleach-y element. The microflora and microfauna living in the root zone are key to high yields and healthy vigor—without bacteria, organic nutrients would be unavailable to roots. Don’t let chlorine kill the good guys!
Chloramines are chemical compounds of ammonia and chlorine that are also often used as municipal water supply sanitizers. Chloramines do not evaporate from water the way chlorine does and many water filters that remove chlorine cannot remove chloramine. The effects of chloramine on your garden are even more detrimental than chlorine.
"Don’t let chlorine and chloramine use your nutrients against you—visit your local hydro shop and source out a filter that removes both substances, not just chlorine."
To avoid the problems caused by these chemicals, invest in a water filter and make sure it takes out both chlorine and chloramine. The improvement you’ll observe in plant health will be considerable, which should translate to a substantial increase in your harvest as well.
Hydroponics and Chelates
Chelates keep nutrients, especially micronutrients, suspended in solution. Without chelates, some of the valuable elements in your hydro system would lock onto each other, forming chemical compounds that are worthless to your plants.
Think of chelates as Teflon coatings for nutrients, keeping things free and available instead of stuck to something. Chelates can be chemical, like EDTA, or organic, like humic acid. All hydroponic base nutrients contain chelates for maximum nutrient availability.
As previously discussed, chlorine is technically a micronutrient. When high-quality hydroponic chelates come into contact with it, chlorine becomes even more likely to enter your plant’s vascular system. In other words, chlorine is even worse for your plants in the presence of high-quality nutrients.
Don’t let chlorine and chloramine use your nutrients against you—visit your local hydro shop and source out a filter that removes both substances, not just chlorine.
Attempting to Bubble Out the Chlorine
Some growers used to ‘bubble out’ the chlorine in their solutions, meaning they would use an air stone and let the water sit out for 24 to 48 hours. With new technology, though, these chemicals are now just too tenacious to evaporate completely using this method. Again, the only reliable solution is a quality water filter.
Most growers who switch from bubbling out to filtering report immediate improvements in plant health and garden performance. I made the switch several years ago and the results have been outstanding.
Water + Oxygen = Happy Roots
When growing in hydroponics or using nutrient solutions, it is important to oxygenate the water. Experienced growers know that ideal water temperatures combined with motion are the keys to a healthy reservoir. It might also surprise you to know that bacteria are another step in the process to improving water.
Beneficial bacteria want an aerobic (oxygen-rich) environment. When we provide cool temperatures and water movement, some strains of bacteria will actually pull in oxygen and make it part of the solution. Do your garden a favor and add a diverse blend of beneficial bacteria to your solution—among the many benefits of these microbes will be white roots and big fruits.
Here we have another conundrum: incorrect pH levels reduce growth; however, correcting the pH level will also alter nutrient levels.
When scientists formulate hydro nutrients, they try to achieve the perfect nutrient ratios. Chemical pH adjusters like pH up and pH down contain phosphorus, potassium and other elements. Although our goal might be to correct our pH level, we end up changing the nutrient levels in the process.
Another danger of pH adjusters is going too far in one direction or the other. If you accidentally drop the pH level to five, you then need to raise it up a bit—but now you’ve added acid and base to the same solution, which creates unwanted salts and altered nutrient ratios.
Now consider the living organisms in your reservoir. We want to encourage beneficial inoculants, not poison them. Chemical pH adjusters in their concentrated form will kill many symbiotic organisms in your reservoir.
When using pH adjusters, add them sparingly. Overwatering and warm water can also cause pH problems—not to mention root rot—so avoid those pitfalls as well. (Read More: The Top 4 Reasons Your pH is Out of Whack)
If you fling some clean water on a pane of glass, you can see that the droplets form into rounded beads. This is the natural tendency of water, due to its surface tension. If you do the same with soapy water, the droplets spread out much farther than they would without the soap. Clean water creates a lump; soapy water creates a film.
My physics professor, Dr. Benjamin Malphrus, used to say “Soap makes water wetter.” Wetting agents like soap cause water to coat surfaces, rather than just rest on them—that’s why we use these products with foliar sprays to achieve an all-over coating effect.
The same rules apply to roots. When wetting agents are used in your nutrient solution, the mix will spread over the surface of the roots, increasing the efficiency of nutrient applications.
Some common wetting agents include coconut extracts, quillaja saponaria (soap bark extract) and organic castile soaps.
Calcium, Magnesium, and RO Systems
Measure the water coming out of your tap with an EC or PPM meter. If your water is like most, it probably contains 150 parts per million (ppm) or even higher levels of unwanted salts. This level of salt in your water limits the amount of inputs you can add.
If your nutrient recipe is designed to achieve 1,300 ppm and you use salt-laden tap water, the results will be over 1,450 ppm. These unintended salt increases might burn your plants or interfere with your nutrient regimen. (Read More: Why Plants Need Salt in Their Diets)
What is that 150+ ppm comprised of, anyway? Often it consists largely of calcium and magnesium. You might think, “Great—I needed that anyway!” but you would be mistaken.
"The particular forms of calcium and magnesium that are contained in municipal water are often the large-molecule variety—and large molecules cannot fit into the small pores on plant roots."
The particular forms of calcium and magnesium that are contained in municipal water are often the large-molecule variety—and large molecules cannot fit into the small pores on plant roots. They are not absorbed by plants, but instead just attract other calcium molecules with a snowball effect.
The only way to reduce salt content is with a reverse osmosis filter. RO filters might seem expensive, but damaged nutrients and calcium lockout can cost more than filtered water. RO units made for the hydroponics industry include carbon and sediment filters to deal with the problems discussed in previous sections, so they have multiple advantages. Like most of my recommendations, the main goal here is healthier plants and bigger yields.
Soaking It Up
When we learn how water and nutrients impact each other we can use them more effectively. Some growers just add a dash of this and a dash of that and top it off from the tap—others achieve their goals by learning about, carefully measuring and thoroughly testing every liquid they use. If you want to grow like a pro, get to know your water!
Written by Casey Jones Fraser