How to prepare large scale hydroponic stock solutions accurately

In this video, I show you why large-scale preparation of hydroponic stock solutions cannot be carried out using the same methods as small-scale preparations. I show you how to perform a small-scale preparation so that you can then use the information obtained to prepare hydroponic solutions of any size.
- W0 is the mass of the empty volumetric 250 mL flask with stopper
- Weighted =116.24g
- W1 is the mass of Ca nitrate for 250mL
- For a final concentration 100ppm of N and 131 ppm of Ca at 1:100 we need 17.36g for 250mL
- Weighted = 17.48g
- W2 is the mass of the full 250 mL flask
- Weighted = 376.77g
- W3 is the mass of water added to 250 mL of final solution
- To calculate W3 = W2-W1-W0)
- 376.77g - 17.48g - 116.24 = 243.05g
- W4 is the mass of Ca nitrate for 300mL
- To calculate W4 = W1*300mL/250mL
- 17.36g*300mL/250mL = 20.8g
- W5 is the mass of water added to 300 mL of final solution
- Conversion factor: W3/250mL=0.9722
- To calculate W5 = 0.9722*300mL = 291.66
(Please notice that the Amazon links below are affiliate referral links. This means that if you click on them I may receive a commission from purchases. There is no additional cost to you, but it helps me to keep posting content for free.)
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[@hanumkas]

My recipe wants me to add Ammonium Nitrate but HydroBuddy wouldn't show in which (A or B) stock solution that needs to be added. Please help me Daniel.

[@ScienceinHydroponics]

You can add ammonium nitrate in either.

[@hanumkas]

@@ScienceinHydroponics ok thanks

[@MrKartman35]

At the greenhouse where I work, we prepare our A&B mixes in 2200 liter reservoirs, but the large surface area of the rectangular tank makes the actual volume of water VERY inaccurate compared to what you're suggesting is necessary. Is this a problem? I'm also making the same recipe at home with no issues (that I can tell anyways). Why is this accuracy so important? The nutrient solution is dosed using EC meters, so the only danger should be a potential imbalance of A to B as far as I can tell (unless I'm missing something).

[@ScienceinHydroponics]

The accuracy of the solution that is fed to plants is the one that matters the most. A proper approach to achieve this is to determine, using accurate small scale preparations, what an accurate dilution of an accurately prepared A or B solution would give, then use that EC as a target for the large scale dilutions from the stock tank prepared with less accuracy. In this case both A and B need to be tested separately on injection, to make sure that they are both reaching the EC target they should, as determined through the accurate tests.
Most facilities are usually within +/-20% of their feeding targets. Plants are very adaptable, so these deviations do not prevent people from growing healthy plants most of the time. However, they can affect your decision making process when you make calls based on what you think you are feeding instead of on what you're actually feeding. It can also cause you to interpret problems that arise the wrong way. Routine testing to ensure the accuracy of the prepared solutions - from solutions taken at the dripper - is a great way to prevent inaccuracies from becoming a problem.

[@speadskater]

One thing that gets me is moisture contamination for the salts. In my greenhouse, the salts are stored in climate controlled areas, but not humidity controlled.

[@ScienceinHydroponics]

Thanks for commenting. Yes, salts that are hygroscopic need to be stored in air-tight containers. Note that even low humidity environments are good enough to keep these salts dry as many of them can dry air to close to 0% humidity.

[@circle4922]

@@ScienceinHydroponics "Note that even low humidity environments are good enough to keep these salts dry as many of them can dry air to close to 0% humidity."
I'm unclear on what you mean by "...as many of them (the salts?) can dry air to close to 0% humidity".
Are you saying the salts will draw moisture into them to the point where the relative humidity (of the container they're in, I'd assume?) is 0%?
And did you maybe mean to say "Note that even low humidity environments are *not* good enough to keep these salts dry as many of them can dry air to close to 0% humidity"?
I'm just a little confused.
Thank you.

[@ScienceinHydroponics]

@@circle4922 Sorry, my mistake! I meant, even low humidity environments are NOT good enough. Some of these salts can actually dry air close to 0% relative humidity, with how hygroscopic they are.

[@circle4922]

@@ScienceinHydroponics Ok. Thank you for the clarification. That makes sense to me now. I figured it was a simple typo (I hoped anyways, haha).
The calcium nitrate I've used, for example, is incredibly hygroscopic, as you know. It basically turns into water droplets within minutes if some of the little balls spill onto a surface.
Thanks again!

[@DarkChild1758]

Why did you weigh 17.48 calcium nitrate when 17.36 is needed?

[@ScienceinHydroponics]

No transcendental reason. Mainly because I didn't want to repeat the measurement.

[@FanRamm2]

Interesting to see that you didn’t use a professional lab scales in this case to be “100% accurate”. Doesn’t need it? I think for trace elements, like Mo it’s must have. Accurate measurements for chelated trace elements most important in my background.

[@ScienceinHydroponics]

You can definitely use better scales for better accuracy. This is especially important when doing research, where you need very tight control to learn what changes are caused by variations in a trace element. However, as far as plant health goes, they tolerate substantial variance in the concentration of these trace substances. It is also not really worth it to be extremely accurate in something like the Mo when you're using industrial grade salts for fertilizer preparation as the Mo impurities found in those inputs will increase your inaccuracy to a big extent.

[@CannabinaTV]

Hey Dr. Daniel, can you explain how can we do this math for us to calculate our own fertilizers mix. Thanks. I live in a country where we cant find many fertilizers brands, so making our own is always cheaper. I always struggle at the dillution part of the calc.

[@ScienceinHydroponics]

I would recommend using the software I developed, Hydrobuddy, to make these calculations. It will be much easier.

[@Bowserkitty]

Do you have a video for beginners?? Like why exact stuff is better and how to get started? 👍

[@ScienceinHydroponics]

Please watch other videos in my channel and leave any specific questions you might have on the comments.

[@ShopperPlug]

I thought making "large scale" hydroponic stock is much more complicated, I was told that the "specific gravity" changes due to larger volume stock than it is with lower volume stock, which means you will need a refractometer to check if the "specific gravity" of the large stock is in the proper range. It's not so simple by just mixing in concentrated chemicals together to make large stock. Maybe 100 gallons of stock is not so large of volume where specific gravity of the stock changes. I also like the fact how you mention about accuracy needed in this video.

[@ScienceinHydroponics]

Thanks for commenting. If you prepare it this way, your solution will be as good as it can be given the errors of the measuring tools you use. People who have problems with variations of the specific gravity have them because they lack a proper preparation procedure (like the one presented here). The specific gravity of your 250mL small scale solution and a 100,000 gallon solution should be exactly the same if you follow the procedure as shown. Measuring this number is useful though - which you can easily do using a pycnometer - is a good way to control that everything went as expected.
Note that this procedure is how I prepare solutions with my clients, we often prepare thousands of gallons of concentrated stock solutions and our specific gravities between small scale lab preparations and industrial scale are usually within +/-2%.

[@ShopperPlug]

@@ScienceinHydroponics Thank You for your reply.

[@liorsilverstein9802]

can you make a video on how you became a hydroponic chemist overcoming the third world (mexico or colombia)?

[@ScienceinHydroponics]

Thanks for the suggestion! I will however keep the videos about the scientific topics rather than my personal life.