Just a quick word on buffering when referring to pH solutions

dcyans

dcyans

Aerojunkie
Just a quick word on buffering when referring to pH solutions. It would not be necessary to use Ph values if all acids were ionized to the same degree, but they are not. For example, the pH of a solution of the following acids at 77 degrees (25C) is as follows:
* Hydrochloric acid: 1.1
* Sulfuric acid: 1.2
*Citric acid: 2.2
*Acetic acid: 2.9
The strength of an acid depends not on it’s total acidity (concentration of molecules), but only on the concentration of hydrogen ions. PH is extremely important in biological fluid systems such as human blood and the fluid of plants. Natural biological systems are protected against catastrophe of sudden influx of acids or bases with built in buffering agents that keep the pH relatively constant. Hydroponic solutions do not have a built in buffering system, organic solutions may have one, but that is entirely dependant on the nature on organic matter in solution. If a hydroponic solution is experiencing too many wild pH swings, control can be had by adding an appropriate buffer to the formula or solution. There are a number of commercial inorganic nutrient formulas available having pH buffering agents. Buffering chemicals need to be compatible with the other chemicals in a hydroponic solution; this is critically important for the buffers employed in biological systems. The two most commonly used buffering mixtures are the Mcllvaine and the Britton-Robinson systems. Mcllvaine buffer is a mixture of citric acid and sodium hydrogen phosphate that buffer pH in the range of 2.2 and 8.0. The Britton-Robinson consists of acetic acid, phosphoric acid and boric acid, plus sodium hydroxide and buffers pH in the range of 4.0 and 11.5. Now comes the good part ;) Citric Acid! Commercial citric acid is produced by a microbiological process employing the mold Aspergillus niger. It is safe to handle, inexpensive, readily available, stimulates growth, performs as a natural chelating agent for trace elements thereby increasing the nutrient values of the plants, and is the ideal pH buffer for hydroponic and bioponic solutions. Pure citric acid is a plant acid with a pH of 2.2. Classified as a weak acid, it is very stable and good for maintaining the pH level desired in a hydroponic nutrient solution. Plant roots will absorb some of the citric acid thereby increasing the citric acid cycle within the whole plant. When citric acid and various microorganisms are incorporated into the nutrient solution, chemical changes occur, activating the Kreb cycle converting citric acid into a number of other plant acids, such as ketoglutaric, succinic, fumaric, malic, oxalo-acetic, and finally degrading to water and carbon dioxide. The citric is well known for it’s role in soil, animals, humans and plants. Research over the last few decades demonstrate plant acids are essential in plant respiration and other basic life processes. The use of citric acid in hydroponics and bioponic nutrient solutions takes these systems one step closer to the natural environment in which plants feel most at home. ;)
 
Great info Dcyans. Is citric acid available from a common source such as OSH, Lowes, or Homedepot? Is white vinegar a good pH down buffer?

What do you think would be a good pH up buffer that brings something to the table?
 
Citric acid can be had through the grocery store in the ethnic section "Sour Salt". As far as pH up I recommend the addition of regular tap water adding little to the mix as possible in terms of TDS and staying off the pH rollercoaster ride whenever possible. Acetic acid (vinegar) does work but is not as stable and buffers little. Citric acid does leave a residue although harmless it can clog sprayers and affect the spray patterns in aeroponic systems. Earth Juice Down is what I've used but now with everything being aero around here I use GH's pH down (phosphorus based) and plain old tap water to raise the pH as that is by far the best pH up.
 
Thanks for the info bro. I never need any pH down as I use the Lucas formula and it always comes out at 5.2. I would like it to be at 5.8. What I am going to do is mix the formula and then put it in a bubble bucket of red lava rock until I get the pH up to 7.0. I know it is going to fall back to 5.2 in a over several days in my system. The low acidic nature of the Lucas formula should leach some of the rare earth from out of the lava as well as minerals. Just a little experiment I am running right now. What is the worse that can happen? lol
 
You must be using RO water eh? In your case try adding a bit of potassium hydroxide (or potash) to the solution also hydrated lime will also raise pH nicely but go sparingly!
 
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PH up

Great Post! For raising my ph I have used Pro Silicate for years with great results. Not only does it raise your ph it has many other great qualities such as supplies higher levels of potassium and silicon to build strong cell walls in plants. The stronger cell walls provide a protective barrier to piercing-sucking insects and invading fungi. Using Prosilicate reduces disease and insect problems, increases stem strength and leaf positioning, improves photosynthesis, and increases heat and drought tolerance. Great stuff.. I really like using it with my clones as it seems to aid in rooting.
 
JabberJaw said:
Great Post! For raising my ph I have used Pro Silicate for years with great results. Not only does it raise your ph it has many other great qualities such as supplies higher levels of potassium and silicon to build strong cell walls in plants. The stronger cell walls provide a protective barrier to piercing-sucking insects and invading fungi. Using Prosilicate reduces disease and insect problems, increases stem strength and leaf positioning, improves photosynthesis, and increases heat and drought tolerance. Great stuff.. I really like using it with my clones as it seems to aid in rooting.
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:thumright: :thumleft:
 
Ok I am on the Ph roller-coaster, as you say. My tap water is 7.5, 120 ppm, temp 75 degrees F. I use AN for nutrients and have the Tower Garden http://www.thetowergarden.com/ , and use Earth Juice Natural Down and I still get these WILD swings in ph from day to day. For example, I set the ph of the solution at 5.3 last night and got up this morning and checked ph and it was 7.9. I changed h2o out on Friday, so this should not be occurring now. Any idea why this WILD swings in pH are happening.
 
AN is known for not stabilizing well from what I've seen over the years. You'll want to let your tap water sit overnight and adjust the pH at the same time, see if it stays close to where it's at. You'll also notice a sediment when using EJ down in the res over time it doesn't hurt a thing BTW ;) Add your nutes the next day and readjust pH if necessary. You did not mention your media of choice rockwool can reek havoc if not preconditioned first. With these systems coir works very well also so I've heard and would also help keep the pH in check. I believe the AN is the culprit here.
 
Thank you for your input, I use rockwool and maybe this along with An is the problem. I am going to go buy a brick of coir and root a few and see if this will help the situation out. But as it sits now, if I keep adding the ph down, will this so any harm to anything? Or I am just shooting myself in the foot?
 
You'll need to switch over to coir completely or simply precondition your RW which is quite easy simply soak your RW overnight in water that been adjusted to a pH of 5. All RW users should know this before they start using the product. One more thing Always rinse your RW under running water to rid it of any and all sediment before conditioning and more importantly only drain do not rinse after preconditioning. Chasing your pH will add to your TDS but it should be fine in your particular case I would recommend all addbacks/topoffs have a pH of 5.0 after nutes are added.
 
You can also get citric acid in 5lb boxes at any industrial supplier (like Mcmaster Carr at mcmaster.com) or commercial food service / restaurant supplier (used to remove dishwasher deposits). It's easy to get.

:cool:
 
Citric Acid

Actually your better off just getting the ph down from GH or actually your EJ bloom makes a real good ph down. Citric acid is not a very reliable ph down imo because its not really stable enough. I also have used fish emulsion as a ph down. Good luck!
 
Hey JJ. In my experience with using fish emulsions the pH has always risen(stablized) after some time bubbling. Which wouldn't make it a very stable pH buffer. ;)

If your using it to just bring the pH down quickly,, then sure it's good. I just wouldn't use it a Hydro setup as a pH down product.
 
I'm lucky OGM (the folks that make Earth Juice among other products) are based in my home town. We get a 1lb container of it for like $6 at the local GreenFire store.

The only problem I've had with it was whe nI decided to make a standardized liquid solution. I mixed about 6-8TBS (can't remember exactly) into 1qt RO water. Worked fine stayed in solution but I started to observe signs of bacterial and/or fungal growth.

It manifested with a cloudy clumpy (not crystaline precipitate) globular formation at the bottom of the container and a black fluffy formation floating on the surface. They both looked like mycellium but can't rule out bacteria in the bottom.

I figured the pH would be so low that only rare extremophiles known as acidophiles could survive it. Apparently the extreme acid loving organisms are more common than I thought.

Now I just mix up a little each watering if my nutes need it. While I'm in transition it comes up perfect every time with nothing but PBP Grow, PBP Bloom, Liquid Karma and Sweet.
 
PharmaPharmer said:
I'm lucky OGM (the folks that make Earth Juice among other products) are based in my home town. We get a 1lb container of it for like $6 at the local GreenFire store.

The only problem I've had with it was whe nI decided to make a standardized liquid solution. I mixed about 6-8TBS (can't remember exactly) into 1qt RO water. Worked fine stayed in solution but I started to observe signs of bacterial and/or fungal growth.

It manifested with a cloudy clumpy (not crystaline precipitate) globular formation at the bottom of the container and a black fluffy formation floating on the surface. They both looked like mycellium but can't rule out bacteria in the bottom.

I figured the pH would be so low that only rare extremophiles known as acidophiles could survive it. Apparently the extreme acid loving organisms are more common than I thought.

Now I just mix up a little each watering if my nutes need it. While I'm in transition it comes up perfect every time with nothing but PBP Grow, PBP Bloom, Liquid Karma and Sweet.
Click to expand...

Read my post above as far as the whitish residue. Citric acid is one of the most stable adjusters but the addition of any additives will of course change things and further adjustments will be necessary always.
 
We find citric acid in our grocery and bigbox stores in the canning section. Usually top shelf, near canning lids and rings, etc.
 
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Well, I sure hope that all that hydro info is still relevant, cuz I read the entire thang this afternoon!
 
citric acid for ph down in hydroponics is not stable.....would rather use the citric but it
never keeps the ph in check for more than 24 hrs..generally less
i use phosphoric
 
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