Hello Bbrush,

Certainly this forum implementation is ancient :S.

Monopotassium phosphate does work as a pH buffer but only efficiently when pH is close to 7.2, when pH is at 5.5-6.5 it will easily move towards 7 with a phosphate buffer. If you are looking to keep your pH below 6.5 then this does not buffer pH efficiently.

However the ammonium ion contained in ammonium monobasic phosphate does buffer pH, not in virtue of classic pH buffering but in an ion-absoprtion sense since plant uptake of anion will be balanced by ammonium uptake. A good nutrient solution uses both phosphate and ammonium to efficiently buffer a solution.

I hope this helps :o)

Best Regards,

Daniel

Here is a link that might be useful: Everything hydroponics

"homehydro the rest is water, 1 percent nitric acid is 99 percent water."

OK, it is like 3% hydrogen peroxide, 3% hydrogen peroxide and 97% water =100%. But then I am still a little confused as the total amounts. Ammonium monobasic phosphate, is that the same thing, 1 percent and 99 percent water?

If the nitric acid is 1 percent, and 99 percent water, that adds up to 100%. Then if you add 0.2-3% ammonium monobasic phosphate, that would equal 100.2% to 103% total. I am a little confused as to how all the parts can equal more than 100%. So I'm sure I would not get the recipy correct.

We have our hydroponic strawberries and tomatoes growing outside in vertical hydro-stackers. We have an automatic 100:1 injector system which uses two 55 gallon drums of nutrients and calcium nitrate to feed the plants. However, to get our very soft PH 10 well water to register around 6 at the planters, we add a gallon of muratic acid to the nutrient barrel when we refill it about every 5-6 weeks. It seems to work as our day-neutral strawberries and indetermanent tomatoes are doing quite well. I notice no one ever mentions muratic acid to bring the PH down on this forum. Are there any negative issues about using muratic acid? At $6 a gallon, it seems like an inexpensive way to bring down the PH.

@barberberryfarmer : Muriatic acid is nothing but concentrated hydrochloric acid so you are adding chloride ions with each addition of this acid. Plants can tolerate chloride levels very well below 100ppm so the actual addition of muriatic acid will most likely not play a very important part if your water's chloride levels are not already very high.

However the problem is that HCl - as a strong acid- only provides a quick fix to pH and significant pH changes are bound to happen as the crop evolves. Lowering pH with a solution such as the one I described before, with nitric acid and ammonium monobasic phosphate not only helps you set your pH but further fights future pH changes.

Definitely if muriatic acid is the best solution economically speaking and your water's chloride levels are low then I see no reason not to use it but you might also consider adding about 10-20 ppm of nitrogen as ammonium to your reservoir to further control pH changes.

@homehydro : To prepare the solution I mentioned you simply need to dilute your nitric acid to 1% and then add 0.2-0.3% by weight ammonium monobasic phosphate. Your final solution is bound to be about 0.8% nitric acid, 0.2% ammonium monobasic phosphate and 99% water. As you see, every time the components of a mixture add up to 100%. Since by adding the ammonium salt you increase the weight of the mixture you effectively reduce the concentration of the nitric acid by a small amount.

I hope this informations helps you guys :o)

Best Regards,

Daniel

Here is a link that might be useful: Checkout my free hydroponics nutrient calculator !

Thanks for the reply,
If I have the recipy correct it's,1% nitric acid and 99% water as a starting point. Then add 0.2-0.3% by weight ammonium monobasic phosphate to the liquid. I will assume that the 0.2-0.3% by weight is a dry weight, and when adding it to the nitric acid solution (liquid weight), the difference between liquid and dry weight is not important.

In other words 16 ounces of 1% nitric acid and 99% water solution (liquid), then add 0.2-0.3% (divide 16 oz by 0.2-0.3%) of that in dry weight of ammonium monobasic phosphate to the liquid. Then the recipy should be correct?

Hello Homehydro,

Yes, prepare whatever weight you want of nitric acid 1% solution and then add 0.2-0.3% of the phosphate by weight. So in your example if you have 16oz of solution you would add 0.032oz (0.2%-0.3%) of ammonium monobasic phosphate. I hope this answers your question,

Daniel

Here is a link that might be useful: Everything Hydroponics

@ homehydro;
which weighs more a pound of flour or a pound of water?
dry weight vs fluid weight are both the same measure. . .
weight. (well actually mass x acceleration).
anyway fluid ounces vs 1/16 of a pound(an ounce in pound-force) are different measures. a fluid ounce in a measure of volume not of weight.
It just so happens that one fluid ounce is the volume of water that weighs 1/16 of a pound (or one ounce)as that is how the english scale was founded.

Yes Daniel that clears it up for me.

grizzman,
"dry weight vs fluid weight are both the same measure. . ."

That's interesting. But I don't think that explanation is entirely correct. I may be wrong but in that example all liquids would weigh the same. Fluid ounces is a volume measurement. At least on my measuring cups 16 oz is always in the same place (2 cups). But if 16 ounces is always equal to 1 pound, then 16 fluid oz of molasses weighs 1 pound, and 16 fluid oz of water weighs one pound also.

But molasses is far more dense than water, and I remember from school that density is a key factor in an objects weight (solid or liquid). I believe that's why they make the distinction between ounces, and fluid ounces. But if plain water is proportional to dry weight, then that can make doing the math easier. Thanks.

Daniel, thanks for the info. I'll definitely have the chloride level checked. But I do have a question about what you said about the PH level changing as the plants get bigger. If my well water stays a constant PH of 10 and I need it to be around 6 when it gets to the planters, why would "significant pH changes bound to happen as the crop evolves". Does the PH needs of the plant (i.e., my strawberry plants) change once it reaches full size? I was under the impression a PH level of 6 allows for the nutrients to be digestable by the plant rather than not if I left the PH at its native 10. If that's not correct, is there a link you're aware of that explains the importance of the various PH levels? Again, thanks for all the information!

Ken

Actually I said water was the liquid used to determine the volume of one fluid ounce. I'm sure the standard would be based on sea level(thus zero pressure) and a certain temperature, but I don't remember that at the moment.
The only time a 'weight' ounce is equal to a fluid ounce is when you're measuring water. Of course, most home scales don't have a level of accuracy great enough to distinguish between say spring water and sea water, but there actually is a difference because of their different densities.
Just remember a fluid ounce ALWAYS refers to a volume. It just so happens that fluids with a very low viscosity (near that of water) will weigh approximately one ounce by weight per one fluid ounce of volume and on most home scales you won't be able to weigh the difference. Of course if you can weigh 20 gallons of spring water and 20 gallons of sea water, I suspect a home scale will show a difference in weight.

Metric FTW.

yeah, I use metric too. It's WAYYYYY easier, especially when calculating ppm stuff. But I know a lot of people, especially in the US, still measure with gallons and teaspoons. (and fluid ounces). I still do when cooking, though I measure dry goods in grams for baking.

Obviously, any liquid has its particular properties including a specific density and this is what I normally call specific weight or relative density.

In fact, this "relativity" or specificity of density is either expressed in kg/m3 (EU) or imperial (BG) as in lb/ft3, respectively slugs/ft3, while in the US people often use pounds per cubic foot. The most common and best reference is water (H2O @ 5°C) and this makes even more sense in metric system, as 1 cubicmeter of water = 1 metric ton and 1000 Liter. Thus 1 Liter of water equals 1 Kilogram and 1 cubic decimeter and finally 1 gram of water equals 1 cubic centimeter and also 1 ml. Expressed in gallons, it looks a bit odd though: = 8.34 lb/gallon. Metric system makes life a lot easier indeed - LOL

Examples of various (relative) densities:

While pure water weights 1000 kilogram/cubic meter (as seen)
Sulphuric Acid at 95% and 20° C weights as much as 1840 kilogram/cubic meter
and liquid Butane @ 25" C, only 600 kilogram/cubic meter

In practice (1): if a fluid weight is given, it refers either to water or fluids/liquids, which density is close or close enough to the one of water. This applies where precision doesn't matter and an approximation is good enough. Cooking recipes for example.

In practice (2): if any precision is required or if we deal with other fluids than "water relatives", a volume unit doesn't say anything about the weight of a fluid, unless the specific weight is known and considered. Thus if using or giving an amount of a specific fluid in volume (for example 1 Litre of Sulphuric acid) we can actually say/deduce how much it weights - that is to say according to the previous example that 1 Litre (33.81 fl oz) of 95% sulphuric acid, weights 1840 gram respectively 1.840 Kilogram.

Daniel,

I know that this might be an odd question but does the pH up recipe have a shelf life, also does it need to be kept in cool dark area.

I was also wondering if you have a recipe for pH up?

I meant does the pH down recipe have a shelf life. You cant edit your posts in this forum.

Hello HomeHydro,

It is very acidic so it can last for a long time, however it will not last for more than 2 years if you store it in a plastic bottle. I would recommend storing the solution in an amber glass flask in a dark closet, this will prolong shelf-life to about 10 years. However always keep in a well-label tightly sealed container in a cool space. The most important aspect regarding shelf life will probably be how well sealed the container is since a leaky seal will make the acid and water slowly evaporate, changing the characteristics of the solution. I hope this helps,

Best Regards,

Daniel

Here is a link that might be useful: Everything Hydroponics

Hello barberberryfarm,

Thank you for your reply :o) I think you misunderstood what I said. The optimum pH for your plants does not change as the plants grow but the pH changes do become more prominent as your plants consume more nutrients. Your plants will change the pH level of the solution with more frequency and your addition of muriatic acid does not provide any help with this problem since it simply "sets" pH but does not help with subsequent buffering effects. Using a pH down solution with ammonium helps to do this. I hope this clears it up :o)

Best Regards,

Daniel

Here is a link that might be useful: Everything Hydroponics

Thanks Daniel,
Yes that helps a lot, I store my nutrients in a dark closet in my room, so I will store the pH adjuster there also. I am not sure what container I will use, but I will make sure it had a tight seal, and if I don't use it all I will likely just make a new batch every year (don't think it cost that much). Just wondering, did you not have any recommendations for pH up recipes?

Hello Homehydro,

Thank you for your reply :o) Certainly, it is a good idea to make it yearly, the cost per gallon is really low. It should not be more than a few cents.

Regarding pH up, the best solution I have found is potassium dibasic phosphate also known as potassium hydrogen phosphate or dipotassium phosphate plus potassium nitrate. It helps you increase your pH while it creates a buffer against pH increases beyond 6.5 (through the phosphate pH buffer) and also an ion absorption buffer using the nitrate ion. I use a 1% solution of potassium dibasic phosphate with 0.5% potassium nitrate. This helps increase pH and provides a buffer against further increases.

I hope this answers your question :o)

Best Regards,

Daniel

Here is a link that might be useful: Download my Free Hydroponics Calculator !

Just to explain it better, the phosphate ion additions buffer the solution against further pH increases while the nitrate ion addition creates an ion absorption buffer that diminishes pH decreases. This has been a great solution for me whenever a pH up addition has been needed in my hydroponic crops :o)

Here is a link that might be useful: Download my Free Hydroponics Calculator !

Thank you Daniel very much for the reply,

To be honest it will be a few days before I can digest what you posted. But I have saved it to a text document, and hope to have time this weekend to look into it.

P.S. Just to let you know, I really appreciate the work you are doing to help people make there own nutrient solutions with the software your developing. If there is any way I can help (I have no experience in that) I would be happy to do what I can to further your research, distribution or what ever I can. I think it's great that someone is willing to help the regular person, without asking an arm and leg.

P.S. I know it cant be free to you, even if only in your time. So If I can help let me know?

Daniel, thanks again for your reply. I had to digest your answer for a few days before responding as I'm new to growing in this matter. What stumped me in your last answer to me was this statement: "Your plants will change the pH level of the solution with more frequency and your addition of muriatic acid does not provide any help with this problem since it simply "sets" pH but does not help with subsequent buffering effects. Using a pH down solution with ammonium helps to do this."

The reason it did was because I use the vertical hydro-stacker system to grow my strawberries and tomatoes. Each stack of 5 planters, with up to 4 plants per planter, gets a little over 1 quart of nutrient solution (2 parts nutrients/98 parts water) 4 times during the day with any excess draining out the bottom planter (onto the ground). Under my thinking, the pH level in the planters is renewed back to around 6 every watering. With this approach, is a "buffer" agent still necessary while the nurients are being taken up by the plants during each 3 hour span between the daytime waterings? Please forgive my slowness as I'm just getting my arms around all of this ... :o)

Hello BarberBerryFarm and HomeHydro,

Thanks a lot for your replies :o) I will answer your posts :

@barberberryfarmer : Oh, ok :o) Since you are using a run-to-waste system in which you do not recirculate the nutrient solution the addition of such a buffer will not be needed and your current muriatic acid solution is adequate. I thought you recirculated your solution - in which case a buffering agent helps - but in this case it will not likely make any difference. However I would advice you to change to a recirculating system for both economical and environmental reasons.

@Homehydro : That's ok :o) take as long as you need, I'll be here to discuss it when you want to. Regarding the software and any help, the best thing you could do right now to help me would be to use the program and give me some comments on what can be improved, what you like, don't, etc. For me the most important thing is to make the program the BEST possible software for home growers so any improvements I can make will be great. Also if you can share the link to the software with other homegrowers and give me their opinion it would also be great :o). Possibly in the future building a recipe and fertilizer database will also be something we would like to do but currently I am interested in getting the software fully developed before starting that journey :o) Thank you very much for offering your help !

Thank you very much again for your replies,

Best Regards,

Daniel

Here is a link that might be useful: Everything Hydroponics

where can you get these chemicals at a lowes/home depot or something

Hello Chriscclay,

You won't be able to get them there, you will have to buy them at a chemical supplier. In the US spectrum chemicals is a very well respected supplier of a very wide variety of chemicals in both small and large scales. Cropking also sells several of the salts and acids discussed above. I hope this helps,

Best Regards,

Daniel

Here is a link that might be useful: Everything Hydroponics

Southern States or other farm stores should be able to get most of that stuff for you.
I get my stuff from a landscape supply company. I just tell them what I want and, if they have to order it, they call me when its in.

lemon juice works for me. you have to experiment to get it right