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Is the calcium in tap water available to plants?
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Fair point, especially if your soil pH is good and has decent buffering capacity. If you run in lower ec substrates like coco or hydro, then adding high Ca water with high alkalinity will lock out other nutrients like iron via precipitation. I guess if your water report doesn’t have really high residual alkalinity, and your grow medium has good buffer capacity, then high Ca tap water shouldn’t be an issue. Otherwise, it’s probably a good idea to correct the pH or remove the salts via RO.
Ca++
Well-known member
Nitric is pretty much all available, but phosphoric about 50%. As 50% isn't, the pH has more reason to stay stable. Though I suspect you know this, others may be interested.
I think you are saying you are in soil. There, the ammonium to nitrate ratio isn't generally a thing. I have my eye on this though. An LED user in soil, just used chicken waste tea, and his plants did some LED stuff. Signs somewhat foreign to us before LED. He saw pH as an indicator, but I lost the thread before it got started.
It's a fledging interest. Revolving around the idea of 10% max nh3 we follow. Looking at how we can't control the nh3 uptake except through pH. Then just what excess nh3 would really do. I'm looking toward K with interest. With the mid leaf stripes on my mind. We know the blue light may drive water out of them more than HID did. Opening the stomata another 10% perhaps. It seems those signs can come on rapidly, like a day, so transpiration increases from pumping up the power seem to tie in. It's a lot of info to manage though, based on the little I know at the moment.
If you have some idea what I'm speaking of, look out for it for me please. You might be doing a test grow of interest regarding the N types and LED use.
A big spanner in my thoughts, is how soil plants actually seem a little more resistant to that.
Hey, I am a soil grower, but had to switch to liquid feeding due to container sizes. I think I know what you are referencing, and I’ll send you a pm with more info so I don’t derail this thread.
Dr.Dutch
Well-known member
Regarding the topic, as long as calcium is dissolved in water, it is plant-available. Calcium in tap water is 100% plant-available.
I assume the smiley is expressing ironyNo calcium in tap water is not available to plants.
No, calcium nitrate does not form when you add nitric acid to your tap water. For calcium nitrate to form, the concentration would need to be so high that it exceeds the solubility of calcium nitrate (which is quite difficult because it is highly soluble). Instead, calcium sulfate and calcium phosphate will form in your solution first, which are both much more insoluble and than not plant-available. And undissolved calcium nitrate is also not plant-available.
I believe you might be confusing something. Phosphoric acid dissociates depending on the pH. At a pH around 6, it exists as H2PO4 and HPO4. Both of these forms are plant-available.
Tap water is an unreliable source of calcium to generalize as a group for everyone to use. If you live in a big City with over a million people vs a small town the water will be different. Recommending tap water to everyone is an unreliable recommendation. If I recommend using tap water that's alkaline I will give a bad recommendation and hurt your plants by the time you get in flowering. If a person is going to grow the best cannabis they can grow, they need to use quality water.
Dr.Dutch
Well-known member
If you know what's in your water and calculate it with, it's not a problem.
You are right that the quality can vary (hardly a problem in my country, I don't know how it is in the US).
But the calcium what is in the water is plant available. Regardless of whether the quantity varies.
You are right that the quality can vary (hardly a problem in my country, I don't know how it is in the US).
But the calcium what is in the water is plant available. Regardless of whether the quantity varies.
12. Water Quality
Tap water can be used if it does not contain high levels of sodium, heavy metals, boron, and bicarbonate. Some water sources can have fertilizer concentrations of Ca, Mg, S, and micronutrients. These nutrients are bioavailable and must be included when formulating the nutrient solution. When tap water cannot be used, the most cost-effective water purification method is reverse osmosis (RO), which removes about 97% of the ions in tap water. For critical applications, RO water is often additionally filtered through a deionization column, which removes 90 to 99% of the remaining ions.
In some locations, the use of tap water can result in accumulation of sodium (Na) in recirculating solutions, which reduces plant growth. Elevated salinity reduces leaf growth and development [120], so keeping Na concentrations below 6 mM (138 ppm) is recommended to avoid salinity problems [121]. Reducing Na and other undesirable ions in solution typically requires discarding some of the solution.
High concentrations of bicarbonate in some tap waters increase the alkalinity of the nutrient solution. Bicarbonate can be neutralized to water and carbon dioxide (which leaves solution) through the addition of acid. Continuous acid injection through an injector may be necessary if bicarbonate concentrations are continuously present.
Although we have high-quality tap water with low levels of undesirable elements at Utah State University, we use RO water for hydroponic research studies.
Principles of Nutrient and Water Management for Indoor Agriculture
Mass balance principles are a cornerstone of efficient fertilizer use and can be utilized to optimize plant nutrition without discarding or leaching solution. Here, we describe the maintenance of closed hydroponic and soilless substrate systems based on mass balance. Water removed by...www.mdpi.com
Dr Dutch you guys are lucky to be able to use your tap water. Most people don't know what is in their water. In the US most tap water is modified to raise the pH to stop heavy metals from leaching into the drinking water. When the tap water pH is 9 or above the calcium is not as available as it is when the pH is 6.2. It doesn't matter how much calcium is there. Personally, my tap water is 500 ppm loaded with calcium but with a 9.5 pH it's mostly unavailable. I never recommend tap compared to quality water.
I think there are some good point being made for both sides, and I think there is actually agreement. However, I believe the differences come down to the use cases and generalizations therein.
Is Ca completely dissolved in tap water at slightly acid, neutral, or slightly alkaline pH plant available? Probably, after all it’s full dissociated and in solution. What is the real world applicability of this? I mean, if I took my pH 8.6 water with 250ppm ca and poured into plants it would cause all sorts of issues. Sure the Ca is available in the water, but at pH 8.6 as soon as that calcium ion sees a phosphate from my soil it’s goin to ppt out as a hydroxyapatite or something. And, as soon as that bicarbonate anion sees a ferrous ion, or manganese ion it’s going to ppt those out of solution as well. So, sure it is “plant available” out of the tap. In the real world though, it’s not great advice to dump high alkalinity tap water on your plants without taking into consideration the other factors. So I tend to agree with creeper on this one.
Is Ca completely dissolved in tap water at slightly acid, neutral, or slightly alkaline pH plant available? Probably, after all it’s full dissociated and in solution. What is the real world applicability of this? I mean, if I took my pH 8.6 water with 250ppm ca and poured into plants it would cause all sorts of issues. Sure the Ca is available in the water, but at pH 8.6 as soon as that calcium ion sees a phosphate from my soil it’s goin to ppt out as a hydroxyapatite or something. And, as soon as that bicarbonate anion sees a ferrous ion, or manganese ion it’s going to ppt those out of solution as well. So, sure it is “plant available” out of the tap. In the real world though, it’s not great advice to dump high alkalinity tap water on your plants without taking into consideration the other factors. So I tend to agree with creeper on this one.
Why should a person think that watering soil or promix with plain tap water of pH 9, or especially nute mixture dissolved in same - even more especially if a good chunk of the N is NH4 - changes the root zone pH to 9?
Or that in the real world, hard water instantly precipitates fert phosphate, or Fe and Mn in their usual chelated forms?
Or that in the real world, hard water instantly precipitates fert phosphate, or Fe and Mn in their usual chelated forms?
If your pH is 9 and your water has high buffer capacity Fe and Mn are going to ppt out pretty quick, especially as the root zone dries up. Likewise phosphate is going to ppt out quite quickly. The solubility constants for these are extremely low. Sure edta and the like can help, but it’s not a magic bullet in all scenarios. It’s true the root zone buffers it’s own pH, but if your dumping liters of pH 9 water with high residual alkalinity it will temporarily overwhelm the root zone buffer capacity. Yes, the roots while gradually bring it back into the ideal range, but one something like cal phos ppts, or Fe ppts and oxidizing to ferric oxide/hydroxide it’s much more difficult to re dissolve.
So to add some more nuance, like you are hinting at, soil and media with high cec can handle tap water better than hydro or soil-less.
So to add some more nuance, like you are hinting at, soil and media with high cec can handle tap water better than hydro or soil-less.
citric acid ftw
A lot of crops worldwide are watered with alkaline water with no problem. Greenhouses. Lawns, gardens, golf courses.
Perhaps you should start your own "is phosphate bioavailable in hydro in the presence of excess calcium at a pH of 9.5?" thread. An account of hydro with tap water, yes, taking account of the starting ppm, which is a constraint especially at the beginning. (the truth is there was not much difference between GH hard water formula and normal):
HPS rockwool heresy and a tent of freebies
contains no: popular clones or seeds, led, cmh, dwc, lst, scrog, sog, lucas, hempy, or anyone else, topping, defoliation, temperature or humidity measurement, added co2, o2, o3, calmag, tea, booster, silica, vitamin, neem, bacteria, fungus, fungicide, pesticide, bug eating bugs. necessities...
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I’m not a hydro grower, so no, I won’t. However, thanks for sharing those are some nice looking plants! I didn’t read every post, but it looked like you were using lemon juice and later on phosphoric acid to correct your pH?
Thanks for sharing friend. I work in a greenhouse's friend and we used acid infectors to lower the alkalinity. The same goes for golf courses here where I live. The reason is the tap water won't work and causes big problems here. Using acid injectors is so easy to use and it's common practice when there's a lot of bicarbonate or carbonate in the water.
If you don't know what's in your water and use it, you are putting unknown ppm that can accumulate in the growing media. Some can get by with it and others can't.
Three Berries
Active member
When you pH down carbonate laden water that releases the calcium and magnesium in free readily available form. Any time an acid (H+) comes in contact with a carbonate (-) it will reduce the atomic charge to neutral. This is an ongoing process through physical contact with the chemical compounds. It's why carbonates are called a buffer. When the carbonates compound charge is reduced to 0, all used up, then the buffering stops, all the metal elements are available until they again react with something and pH will go down or up depending on what is added pH wise.
None of this takes into consideration of what microbes do as far as breaking down compounds in soil. But they use acids too....
None of this takes into consideration of what microbes do as far as breaking down compounds in soil. But they use acids too....
Brother Nature
Well-known member
So in short, tap water nutrients are, of course, available to your plant, but unless you know the makeup of your water, it's probably not the best starting block.
