6 minute read
Water, Water, Everywhere
By Nico Hill
Water is something that we take for granted in the comfort of modern-day living. It’s seen as pure and clean and something we can pop into the kitchen and drink from the tap when needed. Despite all appearing very similar to the eye, there are significant differences between water types, which can be essential to growers for a plethora of reasons.
What Reasons?
Firstly, the background mineral content. These are minerals that contribute to the overall EC reading and can be varied in their make up. These minerals will chiefly be made up of calcium and magnesium (good) or sodium and chloride (bad). The importance of correct mineral ratios is something that doesn´t need much explanation.
Bicarbonates need more explanation. The level of bicarbonates present in water has a direct influence on the pH of both the solution and substrate. In Europe, it is typically measured as dKH(degree of Carbonate Hardness). Analyzing both of these factors can help establish what water you are starting with and what the best way to use it would be.
Why Are Bicarbonates Important?
They help to stabilize the pH levels in a solution, such as the one in your reservoir or substrate. Bicarbonates react with the acid in water and temporarily become carbonic acid before turning into water and carbon dioxide. The reaction goes as so:
H+ + HCO3 = H2CO3 = H2O + CO2 (Acid) + (bi-carbonate) = Carbonic Acid = (Water) + (Carbon Dioxide)
By turning acid into water and CO2, the pH of a solution does not drop too low and remains more stable. This acid could come from either a concentrated nutrient (when you add your base nutes and additives) or activity in a rootzone as the plant takes up nutrients such as potassium. Low (or no) bicarbonates results in unstable pH conditions in your reservoir and substrate. This reaction also goes the other way, so watch out for pH fluctuations when oxygenating reservoirs. Ensuring you have the right levels of bicarbonates means a more stable pH throughout your grow, meaning less chance for nutrient lockout.
What Types Of Water Are There?
Extreme Soft Water
Characteristics:
• EC of <0.1
• dKH of 0-2
• Very low mineral level
• Very low bicarbonate level
Common Problems:
Drastic swings in pH fluctuation. Either on the application of (acidic) nutrients, over time in a reservoir or from changes in the plant nutrient uptake within the substrate during growth. Mineral deficiencies. Very low starting level of essential minerals, such as calcium and magnesium. Especially bad combined with high humidity/low air movement (common in propagating stage).
Soft Water
Characteristics:
• EC between 0.1-0.4
• dKH of 2-6
• Low mineral level
• Low bi-carbonate level
Common Problems: Minor pH fluctuation. Similar as described for extreme soft water, but not as extreme (depending on level).
Minor Deficiencies. Again, similar to the description in extreme soft water, but not as extreme (depending on the level.)
Normal Water
Characteristics:
• EC between 0.4 and 0.55
• dKH of 6-10
• Most nutrients are formulated with this type of water in mind (excluding soft/hard specific versions).
• Expected mineral levels, mostly calcium and magnesium.
• Expected bicarbonate level, aiding pH stability.
Common Problems: Minimal. If issues arise, they’re often brought on by environmental mismanagement (grower error.)
Hard Water:
Characteristics:
• EC > 0.55
• dKH of 10+
• High bicarbonate level.
• Very high mineral level, mostly calcium and magnesium.
Common Problems: pH continually rising. The bicarbonates react over time, raising the pH in your reservoir, pipelines, and substrate. This eventually leads to a deficiency.
Mineral imbalance can be caused by elements being at the wrong ratios (excessive) in the final nutrient solution and/or substrate.
Reacts with concentrated nutrients. Particularly when applying a concentrated nutrient, the excess calcium in the water can react with the concentrated phosphor, forming gypsum in the solution and rendering it useless.
Bad Hard
Characteristics:
• EC > 0.55
• High bi-carbonate level.
• dKH of 10+
• High mineral level but wrong minerals! Mostly sodium and chloride.
Common Problems: pH continually rising. Similar to the description of hard water. High bicarbonates can also interfere and slow nutrient uptake in an organic substrate.
Incorrect/damaging minerals. Rather than useful calcium and magnesium, sodium and chloride make up the majority of the content, posing a risk to your plants, quickly causing toxicity issues in re-circulating systems or substrates with a high CEC.
What To Do?
The best thing to do is to bring your water back to a suitable level. Typically, that would be to get it back to ´normal´ water. Normal water has the ideal level of background minerals and bicarbonates, not just for most formulated nutrients, but also for your plant´s long term growth habits.
Extreme soft water´s super-low bicarbonate level is tricky. Similarly to most soft waters, you can raise the minerals to an EC of 0.4 with the addition of a decent quality CAL MAG product, although watch for pH issues depending on your (low) bicarbonate levels. For most normal water, do nothing! For most hard and bad water, it is best to treat it using R.O (Reverse Osmosis) water.
With most hard water, add R.O water until the overall EC gets down to 0.4, leaving you adequate bicarbonates and useful minerals. With most bad water, use R.O to lower the EC right down to 0.2, then use a calmag product to raise back up to 0.4. This leaves you with a more typical bicarbonate level, and a partially corrected (although, still not ideal) mineral level.
High-Quality H20
Once you have arrived at this point, you are now perfectly placed to begin adding your usual nutrient regime. This is, of course, on the basis that you are getting your water out of a tap. Other water sources will also bring in their own complications. Rainwater will have virtually no minerals, very low bicarbonates, and have contaminates from falling through the air and any guttering. Well water can contain unwanted minerals depending on the source, or contain too much bacterial activity if not dug deep enough. Using pure R.O water sounds good; however, having zero bicarbonates and zero background minerals in leaves you wide open for massive pH swings and/or mineral complications.
Test, Test, And Test Again
Whatever your source of water, you need to test it to make sure you know exactly what is in it, how suitable it is for growing, and whether you need to do anything before adding any nutrients. You can use an EC pen to get an indication, but the cheap and easy-to-use hardness test kits from aquatics suppliers will give more concise information about your water´s content.
Other than contacting your local water board, or testing it for yourself, your local hydro store should be well-versed in all things water-related for your local area, so get down there and pick their brains! Doing so could make more difference to your grow than spending hundreds on the swanky new piece of kit is currently hitting the shelves. 3
BIO
Nico has been a keen gardener for many moons. Bitten by the hydroponic bug back in 1998, and hasn’t looked back since! After many years as a hobby, Nico’s career in Hydroponics had its start working for Aquaculture in Sheffield, the UK’s largest and most forward-thinking grow shops of the time. He was then hired by Hydromag, responsible for the hydroponic content. From there, he has worked with CANNA, as editor of CANNAtalk, author of the research articles, and delivering seminars throughout the UK to grow shops on the finer details of cultivating in a hydroponic environment. Nico is now writing for companies in the hydroponic industry.
