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Cap,
I've read a little bit about the nitrification process and have been wondering if it even occurs in a strictly hydroponic environment as the required bacteria or archaea might not be present.
Also, lots of articles and papers I've been reading seem to say that roots can and do in fact take up ammonium ions through the roots and exude an H+ ion to compensate for the ammonium's positive charge. Maybe plants take up mostly the nitrate form, but I think its false to say they can only take in that form. Also, even though they may only take up a small amount of ammonium, it has a much larger effect on substrate ph then a proportional amount nitrate uptake. Consider the following quotes:
"When roots take up charged molecules, such as ammonium or nitrate, they typically release an oppositely charged molecule to maintain a balanced pH inside the plant cells. Because nitrogen can be supplied as a positively or negatively charged form, the root substrate pH can be altered." Source
"Ammoniacal nitrogen is about three times stronger an acid than nitrate nitrogen is a base." Source
"Uptake of other positively charged nutrients such as potassium (K+), calcium (Ca2+) and magnesium (Mg2+) can also cause the secretion of acidic hydrogen ions (H+), similar to the uptake of ammoniacal nitrogen." Source
Are you regularly testing your media ph Cap? I know you're experiencing stable nutrient solution ph in your res, but I don't think that has much effect on the substrate ph.
"The effect that a fertilizer has on media pH is dependent on the reactions that take place after the fertilizer has been applied to the crop. This reaction is determined by the nutrients (especially nitrogen) contained in the fertilizer, rather than the pH of the fertilizer solution that you can measure with a pH meter." Source
To go along with this I also am starting to feel like the exact ph people water at is not as important as it's sometimes made out to be. I think the nutrient solution ph's most important aspect is keeping all ions in solution and avoiding fallout, not effecting media ph.
If you do give JR Peters a call, let me know what they say. Try asking them about the lack of ammonium nitrogen in their formula if you feel like it.
Essentially, Cap, as for pH being affected by ions:
Negative ions:
-Conjugate bases of strong/weak acids.
-Strong acids fully ionize so ions like Cl-, Br- will stay in solution. THESE DO NOT AFFECT pH (generally speaking) and are called "spectator ions".
-Weak acids will only partially ionize at a given pH value--let's say you put some citric acid in:
Citric acid is a polyprotic acid, so we'll only talk about the first deprotonation for illustration:
The first pKa for citric acid is a 3.15 pH. This means that AT THIS PH the citric acid will be half protonated and half ionized. If we push well below this pH, citric will fully protonate (no ions). For each pH value above 3.15 citric will begin releasing more H+ ions. This is the behavior of a weak acid/base about its pKa/pKb value.
Now lets look at NH3/NH4+
NH3 is a base. NH4 is the conjugate acid of that base.
NH4+ has a pKa of 9.3 which essentially means that above pH 9.3, it will lose protons and revert to NH3. Likewise the pKb value for NH3 is 4.7--meaning that NH3 will start to abstract more protons and become NH4+ when the pH is at or below 4.7.
It gets much more convoluted from here--but you get the picture I think. These things follow a curve along the pH scale--the species are almost never fully ionized or deionized unless you push them well above or below their pKa/pKb values. In fact, the henderson-hesselbach equation predicts for us the pH of a solution containing weak acid/conjugate base depending on their relative ratios (and also allows us to predict the ratios from pH reading and information about how much of the substance is dissolved in total).
The equation:
pH = pKa + log ( [A-] base / [HA] acid )
The brackets [ ] denote "concentration of".
If you go back to the citric example in light of this equation, you will note that the pH = pKa when the ratio of A- to HA is 1:1 (Because the log of 1 is 0). This is why we say the ion species is 50% and the neutral species is 50% of the sample when the pH = pKa value of the analyte.
For fun:
A buffer works in the following way:
Lets say we want to make an NH3/NH4+ buffer.
First we'll add the NH3 to solution, then we will push the pH up so that most of the analyte is in the neutral NH3 state. Then we'll add a salt of its conjugate acid. Ammonium chloride will work.
If we add the ammonium chloride such that the molar amounts are equal to how much NH3 we have (say 1000mol)--we will create a buffer.
When we try to add a base, the NH4 will consume it, when we try to add an acid the NH3 will consume it. This solution will resist pH changes at about the +/- 1 pH level. The buffer becomes weaker in either direction with each additional equivalent of base/acid. The buffer is in effect the strongest when the ratio of NH3/NH4+ is 1:1. The buffer is considered depleted when the ratio is at 10:1 (or about 1 full pH value away from the buffer value)
The spectator ions do play a role in this. They stabilize the NH4+ ion in solution, which keeps the NH3/NH4+ ratios auto correcting themselves based on the pH. Instead they are able to act separately. This is what I meant in terms of it becoming more convoluted. The amount of things to consider in solutions like this is WAAAAY to large to be analyzing it in a nutrient solution. Its difficult enough when we simplify it to NH3/NH4+.
Cap: Anyway to get some bennies without eBay / Paypal?
can you make some cliff notes for me Cap?? lolIm gonna have to read this over a few times.:confused:
can you make some cliff notes for me Cap?? lol
With the school year back in swing, I am back in chemistry mode--which means I am (in my free time) getting back to compiling my Cannabis Chemistry Compendium, to be released here on the farm in thread format.
If you guys can think of any questions you'd like answered--I'd appreciate a line in my inbox. If you have the question, someone else probably has the same one. I feel like with all the mad growing experience that is here, and how helpful its been to me, instead of endeavoring to add to that (it seems sort of difficult to from a singular perspective) I can play to my forte and help out with some of the more general chemistry stuff which can be useful to growers--as well as some discussion about more advanced topics which might enable growers to read chemical literature and such without getting lost.
Matter of fact I may just go post a thread now and ask everyone for their questions.
that is very noble of you.
think you mean pickling "crisp" (not "salt", that's just unadulterated nacl)...or, go to your local grocery store and get 'pickling salts'. Got mine for $3.59, and got milk n eggs on the same trip, no shipping required.
Hey Cap, you listed 6 items in your recipe, Jacks hydro, Jacks Cal nitrate, Cacl2 (Calcium Chloride), MKP (Mono-potassium Phosphate), K2so4 (Sulfate of Potash), Epsom salt, and MOST (Micronutrients). However I noticed you also ordered MAP (Mono-ammonium phosphate) and also Magnesium Nitrate. Are you not running these in your formula? Or are they for your Bloom booster recipe?
I see ttystikk recommends a high level of Cal/Mag for use in Coco, do you have a recipe of making your own as an additive?
think you mean pickling "crisp" (not "salt", that's just unadulterated nacl)
I've been reading around on 'calmag' products and trying to better discern what's going on with the cliché of using them as a coco cure-all. Maybe a 'myth' here? Lots of peeps with more experience on this, but seems to me deficiencies posted here for feedback are typically more one than the other? And often when it really looks like both it's actually more of an N deficiency? Why now the uncanny feeling an angry mob will be quick to object? (maybe not so much in this thread though..)
Anyway, I noticed most of the standard 'calmag' products are nitrate based (yuck, no thanks), and the 'organic' ones sold in jugs tend to be carbonate (a lot better for adjing ratios i think, if you can't bring yourself to buy separate 50lb bags instead).
Yes, that's what I meant! The right stuff does say 'calcium carbonate' in the ingredients, to be certain.
haha, T does know what he's talking about though (while i had to waste $2 on the wrong 4lb box first)calcium chloride, to be certain.
fwiw, carbonates are not very water soluble.
pretty sure i have that covered with mgso4, most, calnit, cacl. i used to buy botanicare cal-mag cause everybody said-so, last jug ran out about a year ago and haven't missed it.cal-mag is there at least in part to help other nutrients get to where they need to go and do what they're supposed to when they get there.
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