When growing hydroponically, there can be changes in reservoir levels, that sometimes, can cause imbalances. You can measure EC, and pH, and water levels for optimal feeding. This guide is for anyone suffering with EC and pH fluctuations in hydroponics systems.
There are 18 different conditions you will find your reservoir in when growing hydroponics. Most have common solutions. Such as a falling EC, which is a good sign, as this means your plants are eating well. A slight raise in EC may be needed.
These 18 conditions, will be broken into two parts. One, where the reservoir water level is falling, meaning the plants are drinking. And two, where the water level is not falling, which means your plants are not drinking.
Before running tests on your reservoir or feed, make sure your EC and pH meters are calibrated, and working properly.
If you are having pH and EC fluctuations, and you need help, then feel free to ask for help in our cannabis growers forum
Check Ec and pH Meters
The equipment you use to check for EC and pH fluctuations in hydroponics, must be good and reliable. You need to ensure the readings are accurate, so you can be sure the levels of EC and pH in your reservoir are correct.
Make sure both meters are calibrated, and clean. Use a second meter or pen, if you have one. You can check the readings on both and see if they’re the same.
The pH in hydro should be between 5.8 and 6.2. If your pH levels are in this range, there is no immediate rush to change things. It is good to let the pH “swing” between these levels. It will give the plants access to a wider range of elements.
The pH of your reservoir, will also change depending on the temperature of the water. Keep res temps around 18c for best results. Also use a pH pen that will adjust the reading according to the temperature of the feed.
A safe EC for a fully grown plant is usually around 1.2 to 1.4. But this will depend on strain, background EC, and brand of nutrients. You should raise the EC gradually, as the plant grows bigger.
For young plants, and seedling or cuttings, start at a very low EC of around 0.2 above your BG EC. As the plants grow bigger, adjust EC accordingly. Raise it by 0.2 at a time, until the plants show signs of excess. The EC may rise without the water level falling. In which case, change the res and raise the EC, as the plant is leeching food.
Hydroponic Grow Mediums
If you’re using rock wool, clay pellets, or another kind of hydroponic medium, then you must make sure the pH is set properly, before planting anything into it. Soak the medium, before use, in pH’d water, and adjust it over 24 hours to ensure it is on point.
Making sure the medium has a pH of 5.8 will give your plants the best start. Some issues can be caused by transplanting your plants into a new medium, that hasn’t been balanced first.
Reading EC and PH Fluctuations in Hydroponics
Now we know the meters are good, and the medium is on point, we can go into the water, EC, and pH levels of your reservoir, to determine what your plants are eating. You can judge this by the EC and pH fluctuations in hydroponics.
This first guide, is for when plants are drinking, but there are fluctuations in the pH and EC of the medium:
The ideal situation to be in, is where the EC is either dropping slightly or remaining static, with a static or slightly rising pH. If those are your readings, then keep doing what you are doing, your plants are feeding and drinking healthily.
A moderate sized cannabis plant can drink around 3 or 4 L of water per day. Some cannabis plants that are very big, can drink up to ten litres of water a day! If your cannabis plants have stopped drinking, it is a cause for concern, and needs to be addressed straight away.
Cannabis Plant Not Drinking in Hydroponics
If the water level of your reservoir isn’t falling, your plants have stopped drinking. Along with this, as the plant isn’t taking in any water, it is taking very little, or no nutrients at all.
In a situation like this, you need to act quickly, your plants will begin to suffer within a few hours if they can not drink. Here is a chart, that easily displays the remedy to the problem:
As you can see in some instances, the EC of your res can rise, even though the plant isn’t drinking. This is happening because the nutrients are moving from the plant, into the medium, through a process called Osmosis. (High concentration, to low concentration).
The osmosis process will always try to balance out the EC, taking from the higher concentration and giving it to the lower concentration, to try and restore balance.
If the EC of the nutrient solution is lower than what is in the plant, then food and water will flow from the plant via the roots, and into the medium, raising the EC.
This also works the opposite way around, if there are more nutrients in the medium, than in the plant, the plant will absorb more, which can cause excess nutrients, and nuit burn.
Some things to note when feeding cannabis plants in hydro
Nutrients will flow around a well hydrated plant effectively and faster than one which isn’t as well hydrated. By feeding your plants at low EC, the plant needs to take on more water in order to get the nutrition it requires.
So by feeding at moderate levels, the plant is forced to drink more.
This will result in a better hydrated plant. Which in turn, will need more food, so it will grow faster.
Feed at moderate levels, it is easier to fix an under fed plant, than it is to fix an over fed one. Monitor the EC, and pH, to follow your plants needs, and feed accordingly.
Pushing the EC until you see signs of nuit burn is damaging to the plants. If your plant is drinking, and the EC of your res is falling, raise the EC a little. On the other hand, if the EC is rising, reduce the the EC a little.
Final thoughts on EC and PH Fluctuations in Hydroponics.
It can sound complicated, but using the picture guides above, you can grow in hydro and follow what your plant needs. Regular checks of water levels, EC and pH will keep you well informed of your plants diet, and if it can eat more, or if you’re pushing it too hard.
If you need anymore help with EC and pH fluctuations in hydroponics, you can find me, and many other experienced cannabis growers in our forum. We have many growers who are experienced in different hydroponic setups. Ask for help! The only stupid question is the one you don’t ask
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7 thoughts on “EC and PH Fluctuations in Hydroponics”
understanding things so much more now
This is an amazing post. I recently installed some fine-grained monitoring of EC and pH and have been trying to understand the relationship between the two. Before, I was severely over-fertilizing my (RDWC) plants and didn’t understand why EC was rising and pH was falling. Now I do. Trying to dial it in.
I am just aa week into flower, and it seems like the sweet spot for stable pH is 500ppm. pH rises very slowly and EC falls very slowly.
Does this seem like it is dialed in? Is this a valid way to make sure I am balancing pH and nutrient levels?? If so, this is a dreak come true.
Welcome to Percys mate, can you start a new thread with some pics and we can get a proper look at whats going on 🙂
14 days into 12/12 and all looks healthy, but keep having to adjust ph up sometimes twice daily with a steady 1.6 ec. Just did a res change 10 days ago and the ph started its downward trend around 4 days after that. I try to keep ph @5.8-5.9, but it has dropped to as low as 5.2. Checked probe calibration – good. Can’t figure why the drops so soon after res change. Checked ph straight out of r/o filter tap and am reading 6.5, could 6.5 r/o water before adding nutes be the problem? A res change every 4 days is/ would be really expensive and extreme. Confounded. Any suggestions?
👍 Good info!
@macky I can comment on this now mate but if I click the link “This article is also published as a forum topic here »” it doesn’t take me to the forum, also clicking the “Forum reply »” doesn’t take me anywhere either, everything else is ok
oooooo, that’s one of those thats took a while lol, nice work Macky 😉