So, rather than purchasing more over priced bottles of pH up and down I have been using something that the plants seem to enjoy. To raise the pH I use silica and to lower it I use organic apple cider vinegar. I figure if you’re going to put something into the water to adjust the pH it might as well be beneficial…. any thoughts?
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Don’t use silica to raise the pH of a reservoir after other minerals are already in there. You can add silica before you mix anything else, but it should never be used to raise the pH of a res with nutes. Baking soda (sodium bicarbonate) is cheaper and more effective.
I forgot to explain why. Hydroponics is about chemistry and chemical reactions. Some reactions intended while at the same time trying to prevent other reactions or interactions. Metal ions, non-metal ions, and neutral ions can bond together if concentrations are high. I’ll use the example of a common 2 part nutrient formula with a part A and B. You always mix the part A in water first, then add part B. This is because calcium (metal) has to be put in one part and phosphate (non-metal) needs to be put in the other part or they’ll bond together creating a salt. Part A can’t be mixed after part B because some unwanted chemical reactions (lockout, precipitation, fall out, etc) would occur when pouring part A into a solution with minerals. Metals and non-metals bond to create salts. Think of two elements attached together at a single point, side by side.
Carbon and silica are neutral atoms and can form bonds on 4 sides. These two elements can be quite volatile when concentrated. Silica can bond to create solids even. Being able to create bonds on four sides is how structures are made. Carbon and silica are like the nails or glue that hold the wooden boards (hydrogen, oxygen, etc) together that frame a house. This is why you always want to mix silica to plain water to dilute it’s concentration. Then add your NPK. If you have a res with a high ppm and then add silica, you’ll see a “white cloud” form in the solution. This is not good and the cloud is formed by chemical reactions with other elements causing bonding when concentrated silica is not diluted in plain water first. You can mix silica to plain water, then use that water with the silica diluted to bump up the pH in your res but you’ll still get a little drop out. I mentioned using baking soda as a cheap pH up because sodium is beneficial with no chance of causing lockout.
The types of bonds I’ve described above are reactions that happen in your reservoir and are not going to be available to your roots when irrigated. Salt bonds can cause real issues over time in the media. They’re always going to occur on some scale. Make that scale as small as possible. This is why Recharge is great for hydro also. Roots exude sugars for microbes to eat. These sugars will mix with salts and other organic matter, be consumed by microbes, then broken down in the microbe and pooped out in an available form for roots to uptake. Good luck. 😉
Check out my nutrient guide if you’d like to go deeper.
https://www.dudegrows.com/mystros-guide-to-cannabis-nutrition/
Now that sir is what I call an explanation. Kudos to you Jmystro in saying that in an understandable way that explains the actual science of what is going on. Honestly I was wondering about this stuff this morning. I use 3 part and always add micro then grow then bloom. Problem is when my ppm isn’t high enough I add more in the same order. Am I screwing up by doing this. Also I am not OP just found this reply extremely interesting. I use ph up and down….would I be better off switching to soda and vinegar? Or do you run into more problems down the road with that.
They need to be mixed in a certain order for the proper chemical reactions to occur like I mentioned above. If you want to bump up your ppm wid-week you have options. In veg, mix the parts as directed in a separate container, like a 5 gal bucket and pour that in your res to top it off. In flower you can do the same or just add a little bloom. Bumpin up your ppm with only the bloom is a cheap “bloom booster”.
Only takes a pinch of soda! I put a small amount in my hot tub and mannnnnnn. Had to dump it. Good question though and I am always thinking about vinegar. Use it in a pinch before. I feel like I was told that it doesn’t keep the ph down as long though.
PSA
Ions by definition are only positive (cations)or negative (anions). There are no neutral ions.
Are you using elemental silicon or potassium silicate or something else?
Carbon is a element and silica is o compound aka silicon dioxide.
Carbon shares its electrons through covent bonds. Organic chemistry.
Salts form by ionic bonds
Ca2+ a positive ion and negative (PO4)-3 make an insoluble salt. Ca3(PO4)2. There is a di and tri basic form that’s for another day. We get into this more below.
The ability to form and dissociate ionic bonds has to do with a lot of factors:
Concentration
PKa – dissociation constant
pH
Temperature
The Solvents and solutes of question
Equilibrium of the solid and ions in the solvent
Let’s just say – Solubility, solubility, solubility
Solubility plan and simple:
Phosphates are insoluble except those of sodium, potassium and ammonium, all of these are cations. You need to avoid forming phosphate salts with other cations aka your hydroponic micro solution. Hydroponic micro solution are always separated from the phosphates(anion) – that’s why you mix them separately. If these salts form you can’t get them back- in aqueous solutions or its very difficult.
I’ll get into this in the first deep dive. Trying to avoid too much chemistry. But you can’t avoid this.
You want something cheap. Amazon potassium hydroxide. You can get 2 lbs for $20.
Add 112.2g of KOH to 1 litter of water to make a 2 molar solution. You just made ph up. At a cost basis of $2.50/liter.
Actually don’t mix it that way. Do this
Take some water about 500mls
Slowly add the 112.2g KOH while mixing- the reaction is exothermic be careful it gets hot
Bring water up to 1 litter.
There you go 2M KOH solution. I did this to see if your paying attention. This is beneficial. Man you can even add blue dye to it. Use it to clean your drains, dissolve bones or make soap.
Use phosphoric acid for pH down.
Or buy some HCl instead. The box stores will have it as Muriatic acid.
Sodium bicarbonate- baking soda should be avoided.
BBBB – your ok adding micro part to an already diluted veg/bloom solution. Concentration is one a the variables of solubility and your veg/bloom is diluted enough. However it’s possible to precipitate the solution in theory – why because
At 37°C using the constant composition method. At a controlled ionic strength of 0.10 mole/liter and Ca/P = 1.333 the precipitation of dicalcium phosphate dihydrate is formed at all supersaturations at pH 5.5. What? Don’t worry not going to happen. But it’s true.
Jmystro is the man and he has done so many great things for the community – listen to him and thank you.
I am just a jackass chemist.
Deep dive v.1
did yo know that the precipitation of salts are actually crystals. These salt crystals take time to form and grow.
You can learn more by studying liquid-solid phase diagrams. The point of concern is the energy of activation where nucleation of salt forms. Nucleation of salt crystal takes more energy to form than growing, this is why if scale is present(this a salt crystal) in your system you will be more likely to have your solution precipitate and are greater risk of lockout.
So what makes salt crystals dissolve. Lets use sodium chloride salt crystals NaCl as an example . Because water also has a negative and positive charge. It’s a good polar solvent. The negative side of water can pull positive ions sodium (Na+1) away from Cl-1 and the positive side of water can pull negative ions (Cl-1) away.
So why can water dissolve/dissociate some salts and not others. Well, it’s the speed in which an ionic bond and be put back together. The equilibrium of the salt crystals and its solvent. Phosphate crystal are pulled apart much slower than they are put back together. Hence precipitation and the crystals grow.
Here’s a table from a Google search
These can be mixed without concerns of precipitation
Generally Soluble Inorganic Compounds
* Ammonium (NH4+), potassium (K+), sodium (Na+) : All ammonium, potassium and sodium salts are soluble. Exceptions: some transition metal compounds.
* Bromides (Br–), chlorides (Cl–) and iodides (I–): Most bromides are soluble. Exceptions: salts containing silver, lead, and mercury.
* Acetates (C2H3O2–): All acetates are soluble. Exception: silver acetate is only moderately soluble.
* Nitrates (NO3–): All nitrates are soluble.
* Sulfates (SO42–): All sulfates are soluble except barium and lead. Silver, mercury(I), and calcium sulfates are slightly soluble. Hydrogen sulfates (HSO4–) (the bisulfates) are more soluble than the other sulfates.
Generally dilute these before mixing.
See baking soaking (a carbonate) can cause lockout and the sodium is not beneficial. Don’t use.
Generally Insoluble Inorganic Compounds
* Carbonates (CO32–), chromates (CrO42–), phosphates (PO43–), silicates (SiO42–): All carbonates, chromates, phosphates, and silicates are insoluble. Exceptions: those of ammonium, potassium and sodium. An exception to the exceptions is MgCrO4, which is soluble.
* Hydroxides (OH–): All hydroxides (except ammonium, lithium, sodium, potassium, cesium, rubidium) are insoluble. Ba(OH)2, Ca(OH)2 and Sr(OH)2 are slightly soluble.
* Silver (Ag+): All silver salts are insoluble. Exceptions: AgNO3 and AgClO4. AgC2H3O2 and Ag2SO4 are moderately soluble.
* Sulfides (S2–): All sulfides (except sodium, potassium, ammonium, magnesium, calcium, and barium) are insoluble.
* Aluminum sulfides and chromium sulfides are hydrolyzed and precipitate as hydroxides.
Too much. Not responsible for typos or other errors.