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Robert Bergman

October 28, 2016

In this article we will discuss:

For the growth of all life, the correct acidity of the growth medium, fertilizers and water is very important. The acidity level determines the quality of the bacterial life, and the metabolic rate of the marijuana plant. Bacteria, which are important for the conversion of fertilizer to absorbable substances thrive best in a neutral environment, which means a pH level of 7. Learn what the best pH, EC/TDS levels are for hydro marijuana plants.

What is pH

What is pH for hydro

The pH is the rate of positively and negatively charged water ions, so in other words, it measures the absorption within a solution. You can figure out the acidity level by how many positively charged ions there are. If the negatively and positively charged molecules are at a balanced ratio, then the environment is considered neutral. Depending on what materials are entered into the solution, the acidity level may become more alkaline or acidic. What determines the pH level is simply the absorption of positively charged ions in the solution (wikipedia).

The pH scale goes from 0 (acid) to14 (alkaline). For a solution to be neutral which means it is non-alkaline and non-acidic, it needs to be at pH level 7. This is a mathematical scale so with a consideration of 10, for every point that the pH level shifts the solution either increases in acidity or becomes more alkaline. When you consider pH level 7, a liquid that has a pH level of 6 is literally 10 times higher in acidity. As for a pH 5 it would be one hundred times higher in acidity. Be very cautious when blending acids and salts because they easily become a lot quite fast.

Download my free marijuana grow guide at this link for more growing tips

In some way or another cannabis plants require trace elements which are restricted to water that is high in pH levels and is not able to be taken in by the plant. Everything that is good for one part of your plant may not necessarily be good for another. For example the needs of trace elements and the roots differ, so you have to figure out a pH that works for every part. You are better off choosing water and nutrient liquids that are somewhat acidic with a pH around 5.5 – 6.5. You can adjust the levels to go up half a point.

Hydro pH levels

Hydro pH levels

  • Excellent – around 5.5-5.8
  • Good – around 5.3-6.5
  • Acceptable – around 5.0-7.0
  • Disturbed nutrient concentration – under 4.5 and  higher than 8.0
  • Permanent harm to the roots – under 3.5 and over 9.0

pH too low. If the pH level is 5 or beneath that, then it is clear that certain elements, especially aluminum are shifting to the point of where they are becoming toxic to your plant. You can stop this from happening by making sure the nutrient liquids stay at a pH of 5.5 or higher. Always take a measurement of the pH of your nutrient water and make the necessary changes prior to feeding it to your plant. One way to raise the pH is by mixing caustic potash into the water, which you can find at a local garden center. More info in the article How to rinse your hydro growing medium

Download my free marijuana grow guide at this link for more growing tips

pH too high. When you have a pH of 6.5 or higher, the calcium, iron and phosphorus ions are constrained to each other. Even though these elements are existing in the solution, they are not expendable. If ever you find this has happened the effects are a severe reduction in the progress of your marijuana plant.

The solution to a pH of 6.5 or above is adding a diluted nitric acid to the nutrient water during the growth stage. Once it reaches the flowering stage add diluted phosphoric acid to it. You can also find these in your local garden center labeled pH- growth and pH- flowering. Just make sure not to overdo it with adding this.

Once you have added something like pH+ or pH- you will need to measure the nutrient water to ensure the pH balance is right. Remember that if you end up raising the EC because of the acidity levels, it could easily result in a decrease in pH levels. Read the artice How to rinse hydro growing medium for more infomation

Hydro EC and TDS values

ec tds levels hydro cannabis

EC stands for Electric Conductivity. You will want to provide your plant with a sufficient amount of nutrients for each stage and an EC meter is how you would determine the nutritional value. You  can also measure the amount of nutrients in TDS (Total Dissolved Solids).

You may find it hard to determine obvious values for the amount of nutrient salts in a solution. The EC will be affected by how big your plant is, how much water, the amount of time you drip, the lighting, the organic EC values of the tap water and the humidity levels in the environment.

Now you can always do things based on your own choices. There are growers who do well working with unusually high nutrient solutions while other growers get excellent results with a weaker solution. The best fertilizers for cannabis plants will most likely have an EC value of 1.2 till 1.5 mS (600 to 750 TDS), which can go as far as 3.0mS (1500 TDS)  if your plant is more matured. The EC will need to be changed if the EC of tap water varies a lot from that of various nutrient solutions averages.

Download my free marijuana grow guide at this link for more growing tips

Let’s say grower 1 has tap water at an EC of 0.5 (250 TDS). This person may prefer the EC be 1.8 (900 TDS) and ends up adding a fertilizer that is at 1.3 (650 TDS).

And then we have grower 2 who has hard water and his tap water is at an EC of 0.8 (400TDS). The grower may prefer a 1.8 EC (900 TDS) as well, so he only needs to put 1.0 EC (500 TDS) amount of nutrients. This amounts to 0.3 EC (150 TDS) fewer than grower 1.

If grower 2 wants to have a similar proportion of fertilizer similar to grower 1, then he need to change the EC to 2.1. Your EC value will be influenced by the amount of drip feedings. So for instance, having a high solutions that is at 2.7 EC, spread over a period of 500 ml per plant is not as much of an issue as drip feedings of 150 ml with the exact solution, six times each day. Using the last situation, the salts end up releasing from the solution causing the EC to go up sky high.

The more you drip, the stronger your nutrients will be. Regardless you have to be aware of what each nutrient in the slabs does. Evaluate the EC and pH of the water that comes out of the slabs every two days. Use a syringe to get a sample of water from the slabs on each 5th and 6th day.

Thanks for reading. Please leave comments or questions below.

Robert Bergman

The founder of I Love Growing Marijuana, Robert Bergman, is a marijuana growing expert that enjoys sharing his knowledge with the world. He combines years of experience, ranging from small-scale grows to massive operations, with a passion for growing. His articles include tutorials on growing... [read more]

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  1. By Michael Davis ,09 Apr 2015
    I would love to have your growth bible
    1. By Ruth Portrum ,19 Sep 2017
      Would these levels apply when using a auto flowering feminized seed
      1. By latewood_ILGM ,25 Sep 2017
        Ruth, Most of the information here is based on controlled grows, and can be interpreted may ways. It is best if you follow these guidelines and learn by watching how your plant responds. I think it would be safe to […]Read More
  2. By e ,15 Jun 2015
    when my tomatoes are flowering , why do it get like powder and fall over and die?
    1. By Jennifer ILGM ,15 Jun 2015
      Hi, I advise you to join the support forum. You can post pictures there and you will get a faster response from our expert growers; Especially in an emergency!
      1. By Stan ,02 Oct 2018
        I only use distilled water for my grow works great
  3. By Stop Magnesium Deficiencies In Marijuana Plants Now! ,03 Aug 2015
    […] the marijuana plant could display signs of magnesium deficiency, even more so in hydro (check these hydro ph levels). This occurs as a result of the pH of the roots not being at the right ratio, which causes the […]Read More
  4. By Hydroponic Marijuana Growing – Learn To Grow Hydro ,14 Dec 2015
    […] the article Best pH and EC levels for hydro growers for more […]
  5. By bud ,24 Feb 2017
    what effect does well water have if water is considerd hard/?
  6. By latewood_ILGM ,28 Feb 2017
    bud, That depends on how hard water is. my well is 220 ppm, and 7,2 PH You can basically grow anything with that even though PH is a bit alkaline. You can also buy nutrients for hard water from some […]Read More
  7. By steven exe ,18 Jan 2018
    hey mr. bergman i just got my seeds.i pickd up a bag of Miracle gro seed starting poting mix would u recamend this for starting my plants?
    1. By latewood_ILGM ,22 Jan 2018
      steven, Yes, you can start your seeds in seed starting mix. I suggest you look around our forum and choose what you will be using before you get started. We have many helpful growers and staff alike that can help […]Read More

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