DIY Alkatronic reagent

[Dennis Cartier]

Randy, I am going to make the leap from the 0.1N standard to my own version diluted from muriatic acid soon. I am down to about 1L left of the 0.1N standard. I assume adding the HCL based 0.02N reagent to a reservoir that has a small amount of the sulfuric acid based 0.02N reagent will not cause any issues?

Also for storing the 0.1N solution. I plan to dilute it in 1L volumetric flasks and then use it 250 ml at a time to create the 0.02N reagent. No issues with storing 0.1N HCL in glass?

 

[Randy Holmes-Farley Verified Community Expert]

Randy, I am going to make the leap from the 0.1N standard to my own version diluted from muriatic acid soon. I am down to about 1L left of the 0.1N standard. I assume adding the HCL based 0.02N reagent to a reservoir that has a small amount of the sulfuric acid based 0.02N reagent will not cause any issues?

Also for storing the 0.1N solution. I plan to dilute it in 1L volumetric flasks and then use it 250 ml at a time to create the 0.02N reagent. No issues with storing 0.1N HCL in glass?

Neither of those things should cause any issue that I can think of.

 

[Reefinmike]

i used the Alkatronic for a year then built my own tester. I went three years of testing 12x a day using labchem 0.1N acid.

4 months ago I decided to be more self reliant and built my own reagent out of hardware store muriatic acid. Testing 12x a day- the yearly cost pans out to ~30¢. The $14 jug will last me 48ish years. The cost savings is nice but irrelevant in the grand scheme of things. Having the experience and know-how to create my own reagent from scratch is priceless. No longer do I need to compare tests from the last bottle of labchem to the new bottle. I already know my reagent and the minor corrections that may be needed so results align with the fancy store bought stuff.

 

[Dennis Cartier]

i used the Alkatronic for a year then built my own tester. I went three years of testing 12x a day using labchem 0.1N acid.

4 months ago I decided to be more self reliant and built my own reagent out of hardware store muriatic acid. Testing 12x a day- the yearly cost pans out to ~30¢. The $14 jug will last me 48ish years. The cost savings is nice but irrelevant in the grand scheme of things. Having the experience and know-how to create my own reagent from scratch is priceless. No longer do I need to compare tests from the last bottle of labchem to the new bottle. I already know my reagent and the minor corrections that may be needed so results align with the fancy store bought stuff.

So spill, what did you find for the dilution ratio for your HCL to get to 0.1N? Was it 99:1?

 

[gbroadbridge]

So spill, ...

Unfortunate turn of phrase ...

 

[Reefinmike]

So spill, what did you find for the dilution ratio for your HCL to get to 0.1N? Was it 99:1?

It was.

i used lowes 20 baume/ 31.5% muriatic acid which pans out to 10.0N. I made the dilution in steps and two separate batches as an attempt at proving my process. Without any modifications, the reagent is roughly 5% stronger than “lab grade 0.1N acid”. I could
Make it identical if I wanted… it’s just a number so I didn’t bother.

I based my diy auto tester off of Randy’s diy alkalinity test using a smaller sample and 0.02N reagent instead of 0.1N. A 55.9ml sample volume is the perfect size such that every ml of reagent needed to reach 4.50pH equals 1dkh. A 55.9ml sample of 9.2dkh water Will require 9.2ml of reagent to see a pH of 4.50 or lower. I ran my tester titration style for a couple month’s testing 24x a day. I noticed that every 0.1ml of reagent correlated to a 0.1pH drop when within 1.0 of the 4.50 target. This led me to a different testing method- add a set amount of reagent for my target alkalinity and interpret the results based on the end pH. For example- say my target alkalinity is 9.20. The water is actually 9.45dkh. 9.20ml of reagent is added to the sample and the resulting pH is 4.75. 9.00dkh sample water will have a pH of 4.30.

long story short, I switched to the diy reagent without a hiccup… i just had to adjust my reagent dose from 9.2ml to 8.8ml.

 

[Reefinmike]

It was.

i used lowes 20 baume/ 31.5% muriatic acid which pans out to 10.0N. I made the dilution in steps and two separate batches as an attempt at proving my process. Without any modifications, the reagent is roughly 5% stronger than “lab grade 0.1N acid”. I could
Make it identical if I wanted… it’s just a number so I didn’t bother.

I based my diy auto tester off of Randy’s diy alkalinity test using a smaller sample and 0.02N reagent instead of 0.1N. A 55.9ml sample volume is the perfect size such that every ml of reagent needed to reach 4.50pH equals 1dkh. A 55.9ml sample of 9.2dkh water Will require 9.2ml of reagent to see a pH of 4.50 or lower. I ran my tester titration style for a couple month’s testing 24x a day. I noticed that every 0.1ml of reagent correlated to a 0.1pH drop when within 1.0 of the 4.50 target. This led me to a different testing method- add a set amount of reagent for my target alkalinity and interpret the results based on the end pH. For example- say my target alkalinity is 9.20. The water is actually 9.45dkh. 9.20ml of reagent is added to the sample and the resulting pH is 4.75. 9.00dkh sample water will have a pH of 4.30.

long story short, I switched to the diy reagent without a hiccup… i just had to adjust my reagent dose from 9.2ml to 8.8ml.

To clarify-

i measured 1,000ml 10.0N HCl using a 500ml volumetric flask and combined it with 9,000ml RODI for 10.0L 1.0N acid

then take 1,000ml of 1.0N and combine with 9,000ml rodi for 10.0L of “0.1N”

1L muriatic and 99L rodi would also work but then you’re having to store decades worth of reagent

 

[pixelhustler]

This is my recipe:

To make 5L of alkatronic reagent

100 ml 1M HCl plus 4900 ml water

Instructions:

1. Fill a 100 ml volumetric flask with 1M acid
2. Put the acid in a 1L volumetric flask and fill to 1L with ro water
3. Add the solution to the alkatronic feed container.
4. Add 4 more L RO water to container.

Do you dump the reagent back into your tank? I’m nearing the end of my OEM .1N bottle and would like to go DIY. Just want to make sure HCl it’s just as safe as sulfuric acid to dump into the tank

 

[dwest]

Do you dump the reagent back into your tank? I’m nearing the end of my OEM .1N bottle and would like to go DIY. Just want to make sure HCl it’s just as safe as sulfuric acid to dump into the tank

Yes, right back into the tank.

 

[Asthix]

For the curious, i do the same for my Xepta Autobalance since the release (about 2 years now) :
4000ml rodi + 18.1ml HCI 23%
Should be 0.033M if I'm not wrong

 

[biom]

Do we know normality of the acid Salifert are using? I have several bottles of indicator dye leftovers from years of testing alk with Salifert and want to use them instead of throwing in the trash can

 

[gbroadbridge]

Do we know normality of the acid Salifert are using? I have several bottles of indicator dye leftovers from years of testing alk with Salifert and want to use them instead of throwing in the trash can

Sort of.

KH Keeper uses 0.02N and provide the following table for users to verify their dilution from their concentrated 0.2N.

I don't understand why there is an slope rather than a simple offset.

 

[Dennis Cartier]

I don't understand why there is an slope rather than a simple offset.

I was just wondering the same thing. There must be some rounding involved that is causing it.

 

[Randy Holmes-Farley Verified Community Expert]

Do we know normality of the acid Salifert are using? I have several bottles of indicator dye leftovers from years of testing alk with Salifert and want to use them instead of throwing in the trash can

I do not.

 

[JimWelsh]

Do we know normality of the acid Salifert are using? I have several bottles of indicator dye leftovers from years of testing alk with Salifert and want to use them instead of throwing in the trash can

According to this: http://www.salifert.com/instructions temp/kh-alk profi-test.pdf 1 mL of Salifert reagent will neutralize 5.71 (actually 16 dKH / 2.8 = 5.7143) meq/L in 4 mL of sample. That means that the normality of the acid is going to be 5.7143 * 4 = 22.857 mM, for a normality of 0.0229 (rounded to sane sig figs).

 

[biom]

Thanks Jim! Very helpful I was just starting to calculate by myself and was going to ask you or Randy to check my math. I have citric acid in hand and I remember it is tribasic so I should divide molarity by 3 to achieve same normality ? Do I remember correctly?

 

[JimWelsh]

Thanks Jim! Very helpful I was just starting to calculate by myself and was going to ask you or Randy to check my math. I have citric acid in hand and I remember it is tribasic so I should divide molarity by 3 to achieve same normality ? Do I remember correctly?

Don't use a weak acid for this. Use HCl or H2SO4.

 

[BeanAnimal]

You mention labchem batch to batch... do you actually find that much of a difference?

 

[Oldreefer44]

I have been testing twice a day for 10 months using the Focustronic reagent. So roughly 300 days. At $110 dollars (currently) for 4 liters. A rough estimate is that there is still roughly 40% (conservative estimate) left so another 120 days worth. At roughly 13 cents per test It is definitely not worth it for me to worry whether a home made formula is done correctly unless one is testing several times a day. Not sure the value of that since two tests, IMO, is enough to give one all the info they need.

 

[Randy Holmes-Farley Verified Community Expert]

Don't use a weak acid for this. Use HCl or H2SO4.

Expanding on Jim's comment, citric acid has 3 pKa's, at pH 3.1, 4.7, and 6.4.

If you are trying to use it for a titration to the low 4's, it becomes complicated to know how many protons have been released from the citric acid at any given pH during the titration.