Mixing reference solutions?

[ColeMan]

So Tom Barr says on a thread in which I inquired about buying a good test kit:

"Do yourselves a favor, make some reference solutions.
Make a set of PO4(0.2ppm, 1ppm, 2ppm), NO3(2ppm, 5ppm, 15ppm), KH(17.86ppm, 71.44ppm), GH(17.86ppm, 71.44ppm) solutions.

Make 500mls of each and then get some good bottles and keep them around.
Check the test kits when you test your tank water about once every 3-6 months. Not hard, then you are lot more certain."

I'd like to mix up some reference solutions, as I'm getting ready to dish out some dough for some Lamotte test kits and want to ensure there accuracy both short and long term.

Using Tom's advice, I'll make a of PO4(0.2ppm, 1ppm, 2ppm), NO3(2ppm, 5ppm, 15ppm), KH(17.86ppm, 71.44ppm), GH(17.86ppm, 71.44ppm) solutions.

I found a link to mix PO4 and NO3 solutions, but what about KH and GH reference solutions?

[Left C]

Here's a revised version of the link that you might of used ColeMan, but there's no GH and KH reference solutions on it.



Directions for Making NO3 and PO4 Reference Solutions III

You will need the following:
- 1 liter of distilled water
- 500 mL graduated cylinder
- 50 mL graduated cylinder
- 1 mL or 3 mL pipette or another device to measure small mLs of solutions
- scales that are accurate to two decimal places
- KNO3 and KH2PO4 dry fertilizers.



Here's a way to make 10, 20, 30, 40 and 50 ppm NO3 reference solutions:

Add 0.70 grams of KNO3 to 429 mL of distilled. This makes a 1000 ppm NO3 solution. (It's really a 1000.72 ppm NO3 solution.)

Add 2 mL of the 1000 ppm solution to 18 mL of distilled water. This makes 20 mL of a 100 ppm KNO3 solution.

Add 15 mL of the 100 ppm solution to 15 mL of distilled water. This makes 30 mL of a 50 ppm KNO3 solution.
Note: You can use this for the 50 ppm NO3 reference solution.

To make a 10 ppm NO3 solution:
Add 2 mL of the 50 ppm solution to 8 mL of distilled water. This makes 10 mL of a 10 ppm NO3 solution.

To make a 20 ppm NO3 solution:
Add 4 mL of the 50 ppm solution to 6 mL of distilled water. This makes 10 mL of a 20 ppm NO3 solution.

To make a 30 ppm NO3 solution:
Add 6 mL of the 50 ppm solution to 4 mL of distilled water. This makes 10 mL of a 30 ppm NO3 solution.

To make a 40 ppm NO3 solution:
Add 8 mL of the 50 ppm solution to 2 mL of distilled water. This makes 10 mL of a 40 ppm NO3 solution.




Here's a way to make 0.1, 0.2, 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 ppm PO4 reference solutions:

Add 0.70g of KH2PO4 to 489 mL of distilled water. This makes the 1000 ppm PO4 solution. (It's really a 999.04 ppm PO4 solution.)

Add 1 mL of the 1000 ppm solution to 9 mL of distilled water. This makes 10 mL of a 100 ppm PO4 solution.

Add 2 mL of the 100 ppm solution to 18 mL of distilled water. This makes 20 mL of a 10 ppm PO4 solution.

To make a 0.1 ppm PO4 solution:
Add 1 mL of the 10 ppm solution to 99 mL of distilled water. This makes 100 mL of a 0.1 ppm PO4 solution.

To make a 0.2 ppm PO4 solution:
Add 1 mL of the 10 ppm solution to 49 mL of distilled water. This makes 50 mL of a 0.2 ppm PO4 solution.

To make a 0.5 ppm PO4 solution:
Add 1 mL of the 10 ppm solution to 19 mL of distilled water. This makes 20 mL of a 0.5 ppm PO4 solution.

To make a 1.0 ppm PO4 solution:
Add 1 mL of the 10 ppm solution to 9 mL of distilled water. This makes 10 mL of a 1.0 ppm PO4 solution.

To make a 2.0 ppm PO4 solution:
Add 2 mL of the 10 ppm solution to 8 mL of distilled water. This makes 10 mL of a 2.0 ppm PO4 solution.

To make a 3.0 ppm PO4 solution:
Add 3 mL of the 10 ppm solution to 7 mL of distilled water. This makes 10 mL of a 3.0 ppm PO4 solution.

To make a 4.0 ppm PO4 solution:
Add 4 mL of the 10 ppm solution to 6 mL of distilled water. This makes 10 mL of a 4.0 ppm PO4 solution.

To make a 5.0 ppm PO4 solution:
Add 5 mL of the 10 ppm solution to 5 mL of distilled water. This makes 10 mL of a 5.0 ppm PO4 solution.

[ColeMan]

Thanks for the link...looks like I might need to wonder over to the barr report to find out about the KH/GH solutions...

[Left C]

Originally Posted by ColeMan

Thanks for the link...looks like I might need to wonder over to the barr report to find out about the KH/GH solutions...

You're very welcome.

The one that I just posted only requires scales that will measure to 2 decimal places instead of 3. Also, all you need is 1 L of distilled water to make both solutions.

This is the older version, but it still works fine.
http://www.barrreport.com/estimative...st-left-c.html

[ColeMan]

I've got a scale that will weigh grams to the tenth - not hundredth. Do you think I need to invest in a different scale? I'm sure it's pretty important to get the .70g right on the money - .75 would screw things up pretty good, huh?

[Left C]

Originally Posted by ColeMan

I've got a scale that will weigh grams to the tenth - not hundredth. Do you think I need to invest in a different scale? I'm sure it's pretty important to get the .70g right on the money - .75 would screw things up pretty good, huh?

Your starting solution can always be a larger volume and this would narrow down the possible error.

Instead of adding 0.70 grams of KNO3 to 429 mL of distilled water; you can double it and add 1.40 grams of KNO3 to 858 mL of distilled water.

0.70 grams of KNO3 in 429 mL of distilled water is 1000.72 ppm of NO3 and so is 1.40 grams of KNO3 in 858 ml of distilled water.

Let's check the possible error factor.
Let's say that your 1 decimal place scales actually gave you 0.75 grams instead of 0.70 grams. You have 1072.2 ppm then. That's an error of 7.1%

Now let's use the doubled amount and your scales gave you 1.45 grams instead of 1.40 grams. You then have 1036.46 ppm. That's an error of only 3.6%

Then you have to ask yourself, "is this good enough for your use?" Maybe or maybe not.

You can play around with numbers by hand or on the fertilator, Chuck's Windows based fert calculator or any other calculator to make your own 1000 ppm solution that will be close enough for your use.

Let's try one more example. You use 1 liter of distilled water for your solution. You weigh out 1.6 grams of KNO3 and that gives you 981.28 ppm. If you weight out 1.7 grams of KNO3 and that gives you 1042.61 ppm. Now let's say you figure out a way to weigh very close to 1.63 grams. That will give you 999.68 ppm or an error of 0.03%. That's very good!

It goes without saying that you can do the same kind of number crunching to get a very close to a 1000 ppm solution of PO4 too.

Does all of this babbling make any sense. I'm trying to help you use the scales that you have. One of the reasons that I chose 0.70 grams for making these solutions is for the people that have scales like yours that weigh to one decimal place to give you and them a very good chance of making good reference solutions. If you used scales that are accurate to 2 or 3 or more decimal places. That would be even better.

Also, you can use another starting solution other than a 1000 ppm one. It just boils down to the math and how accuract that you can measure these dilution solutions.

[Left C]

Originally Posted by ColeMan

So Tom Barr says on a thread in which I inquired about buying a good test kit:

"Do yourselves a favor, make some reference solutions.
Make a set of ... KH(17.86ppm, 71.44ppm) ...

Bill would probably make these KH reference solutions for you. http://liquidarthome.net/khstandard

[ColeMan]

Hey man...thanks - you really answered my question in a very sensible, logical way. I'm over to check out that link right now.

[Left C]

You're very welcome, Coleman.

I sent Tom Barr this newer reference solution how to. I believe that it is OK to post what he said to me: "Thanks, now go forth and post everywhere that have hobbyists that use garbage test kits that sorely need calibration!

I'm amazed that folks will pay 250$$ for a 17 gallon ADA tank, then say they test all the time with a 8 dollar NO3 test kit claiming they do not need a Lamotte nor calibrate the cheapo test kit.

I gave up trying to get folks convinced to test right.
So I figured EI would resolve a lot of that, water changes are easier for most to do/rationalize and understand.


Thanks,


Tom Barr"

Then I sent this response to Tom Barr: "It's on TPT right now because ColeMan mentioned making reference solutions."

Left C

[ColeMan]

I agree wholeheartedly, and EI does solve this problem - to an extent. Regardless of my tank's health (or lack thereof), I'd like to be "in the loop" so to speak, in regards to my tanks chemistry. I figure that a thorough understanding of the tank's chemistry (via accurate testing) combined with a visual reference of tank health (looking and seeing how things are doing) will allow me a better overall understanding of aquarium dynamics.

[plantbrain]

EI is a method to address a human, not an aquatic plant issue.
I know folks just will not do it.

The irony is I test a lot myself.
However, I tend not to test like most folks either.
I cannot bet that I'm going to be consistent for more than a short time frame.

So I freeze the water samples and take them to the lab and run them when we run 400 NO3 samples etc. Or I want to know if maintaining at least 50ppm of K+ via K2SO4 will cause any growth issues for a certain species of plant.

So most of the test I do are more to answer a question rather than monitoring.
If you can rely on the test kit's accuracy, then they become useful and you can tweak and modify the dosing routines based on those readings.

However, even so.............what does 10ppm of NO3 really tell you as far as the plants are concerned?

Will 10ppm of NO3 look the same in every tank to all plant species?
Or should we use the plants themselves and consider all the nutrients, and place more weight on CO2 and light intensity and duration?

These are subjective arbitrary choices we make, some are good, but some can be bad. Be careful in seeking more than is really there and that will answer the question/s you may have.

Regards,
Tom Barr