DIY Alkatronic reagent

[dwest]

According to @dwest 50ml of 1M sulfuric will make 5 liters of reagent.

If correct then, 10ml of 1M sulfuric will mix with 990ml of rodi.

I think the confusion might be from the fact that when you buy alkatronic reagent (at least in the past), it was 0.1N. You had to dilute to 0.02N to use it.

 

[Kershaw]

I think the confusion might be from the fact that when you buy alkatronic reagent (at least in the past), it was 0.1N. You had to dilute to 0.02N to use it.

I read through all the pages of this thread. And there seemed be inconsistent information. But I am far from a chemist and am just looking for a recipe that will work with what I bought. I need easy math lol.

 

[dwest]

I read through all the pages of this thread. And there seemed be inconsistent information. But I am far from a chemist and am just looking for a recipe that will work with what I bought. I need easy math lol.

If I were making it, I would use 10 ml of your 1M (2N) sulfuric acid and 990 ml water.

 

[Kershaw]

If I were making it, I would use 10 ml of your 1M (2N) sulfuric acid and 990 ml water.

I’ll try that. Just realized I need to order the small tubing for the alkatronic. Thank you!

 

[Asthix]

Oh oh. I was just reviewing this thread because I am again facing the prospect of coming up with a DIY replacement for the OEM reagent. The 4L of Coralvue reagent that I was able to purchase for $70.49 is now $154.00 since Coralvue stopped selling their version and my LFS can only get the BRS version.

I did work out the required dilution factor (1:99) a couple of years ago for a 20 baume 4L bottle of muriatic acid I have on hand, but your comment was years before that, and I am now wondering if this means that the 4L bottle would have become less concentrated in the meantime. If so, this would negate the possibility of using it as a suitable replacement for the OEM.

@Randy Holmes-Farley can you comment on the accuracy that muriatic acid will diffuse through the PET bottles it comes in?

Didn't know about that but i'm using my DIY Reagent for the last 4 years with no issue at all.
I make 5L batch that got used in about 6 month with not much difference from beginning/end.
I'm curious where you got this information, maybe with our/store concentration that's not an issue.

 

[Dennis Cartier]

Muriatic acid doesnt work because it evaporates to the air. It also diffuses through the walls of a pet bottle.
For a onetime measurement its good. Sulfuric acid does not evaporate in low concentration. 98% leaves a smoke that will damage Your lungs. If the air humidity is low spill will become more concentrated and cause rust on metal.
I would use citric acid. Does not evaporate or interact with air humidity. But of coarse the water its solved in can evaporate if kept open.
I would use drip bags as in a hospital to minimize the evaporation.

Didn't know about that but i'm using my DIY Reagent for the last 4 years with no issue at all.
I make 5L batch that got used in about 6 month with not much difference from beginning/end.
I'm curious where you got this information, maybe with our/store concentration that's not an issue.

The post that led me to pose the question is quoted above. Hopefully Randy will shed some light on the veracity of the statement.

 

[Randy Holmes-Farley]

I’m addressing the top quote? It does have several statements that I think are untrue or misleading.

Citric acid does not seem at all suitable for doing seawater alkalinity titrations. Alk titrations are usually done with a strong acid. That is, an acid (HA) where at any pH attained in the titration, all if it is in the ionized state, H+ and A-. Citric acid is a weak acid with pKa values for its three releasable protons at much higher values, and even at pH 6, much of it is not fully ionized.

One could do an alk titration with it, but in preparation for that complex experiment, one would need to first determine exactly how ionized the citric acid is at various pH values near the normal pH endpoint of an alk titration (low to mid 4’s).

 

[Randy Holmes-Farley]

The comments about muriatic and sulfuric acid seem misleading. Folks are not using highly concentrated acids for alk titrations.

0.1 N HCl and H2SO4 are not releasing to the air to any important extent. In fact,without looking carefully into it, I’m not even sure whether at very long times open to the air, 0.1 N HCl gets stronger or weaker over time. It will not penetrate plastic to any important extent.

 

[Dennis Cartier]

The comments about muriatic and sulfuric acid seem misleading. Folks are not using highly concentrated acids for alk titrations.

0.1 N HCl and H2SO4 are not releasing to the air to any important extent. In fact,without looking carefully into it, I’m not even sure whether at very long times open to the air, 0.1 N HCl gets stronger or weaker over time. It will not penetrate plastic to any important extent.

Thank you Randy.

 

[Dennis Cartier]

The comments about muriatic and sulfuric acid seem misleading. Folks are not using highly concentrated acids for alk titrations.

0.1 N HCl and H2SO4 are not releasing to the air to any important extent. In fact,without looking carefully into it, I’m not even sure whether at very long times open to the air, 0.1 N HCl gets stronger or weaker over time. It will not penetrate plastic to any important extent.

Would that apply to 10M muriatic acid as well Randy? I would be using 10M HCL (muriatic acid) to dilute down to 0.1N.

I just want to make sure that the concentrated solution, which could last me for a very, very long time, would not slowly weaken over time.

 

[Randy Holmes-Farley]

Would that apply to 10M muriatic acid as well Randy? I would be using 10M HCL (muriatic acid) to dilute down to 0.1N.

I just want to make sure that the concentrated solution, which could last me for a very, very long time, would not slowly weaken over time.

If left open, I am not certain if it gets stronger or weaker over time. The answer may depend on the humidity. If it is generally kept closed, it’s no concern.

HCl is a curious situation since both the HCl and the water can evaporate. In a mix that is 20.2% HCl, then you can boil it and even though both water and HCl are leaving, the concentration is unchanged. At lower HCl it gets more concentrated as it boils until you reach 20.2%. At room temp open to zero humidity air it will concentrate. In humid air, the effect will depend on humidity. At 100% humidity it will weaken.

Best to keep them closed when not in use. lol

 

[Dennis Cartier]

If left open, I am not certain if it gets stronger or weaker over time. The answer may depend on the humidity. If it is generally kept closed, it’s no concern.

HCl is a curious situation since both the HCl and the water can evaporate. In a mix that is 20.2% HCl, then you can boil it and even though both water and HCl are leaving, the concentration is unchanged. At lower HCl it gets more concentrated as it boils until you reach 20.2%. At room temp open to zero humidity air it will concentrate. In humid air, the effect will depend on humidity. At 100% humidity it will weaken.

Best to keep them closed when not in use. lol

Ah, OK, so no issue if tightly closed.

Thanks Randy

 

[gengar800]

Just wondering, ppl who bought muriatic acid from hardware store. Are you worry about the contamination from the muriatic acid that are industrial grade but not lab grade and add the waste water back to the tank ?

 

[ReeferBud]

Is there any benefit to using muriatic acid over sulfuric acids?

Just buy a 500 ml 2N bottle of sulfuric acid.

Costs $20 and lasts me over a year because of the higher concentration.

 

[Randy Holmes-Farley]

Is there any benefit to using muriatic acid over sulfuric acids?

Just buy a 500 ml 2N bottle of sulfuric acid.

Costs $20 and lasts me over a year because of the higher concentration.

No, there is no preference for hydrochloric acid over sulfuric acid of similar quality.

 

[thatmanMIKEson]

No, there is no preference for hydrochloric acid over sulfuric acid of similar quality.

how do they differ only in concentration? or are you saying its better to use sulfuric acid, there is no preference to use hydrochloric acid over sulfuric?

not mentioning quality.

 

[Randy Holmes-Farley]

how do they differ only in concentration? or are you saying its better to use sulfuric acid, there is no preference to use hydrochloric acid over sulfuric?

not mentioning quality.

I’m saying it doesn’t matter. The only difference is whether the bystander ions that don’t do anything are sulfate or chloride.

 

[Noobreef]

Hi everyone! Will be making my own alkatronic solution using sulfuric acid soon using the 1m 2N solution., however ive been seeing people posting that they have the options to use muriatic acid or hydrochloric acid as well. Are there any differences in the readings using either one of the three?

Also, can i dose the diluted sulphuric back into the tank or must i lead to through a wasteline and topoff saltwater?

 

[dwest]

You can use either sulfuric or hydrochloric acid (muriatic is hydrochloric). Just be sure to dilute either correctly.

I use HCl and put the waste back to the tank. I’ve been doing that for over 4 years without issue.

 

[Dennis Cartier]

I finally made the leap to using muriatic acid. I had been dreading doing the cut over. I had calculated the required dilution ratio a few years ago (https://www.reef2reef.com/threads/diy-alkatronic-reagent.639360/post-11029448), but had been hesitant to actually make the change. The reason for my hesitation is that I had zeroed in on the dilution factor using a slightly odd technique using a Hanna checker and a stale off the shelf alkalinity standard and was not too confident that I had not messed it up. This would be the first time I actually mixed up any reagent using the calculated ratio.

The ratio that I calculated is 99:1. So 10 ml of muriatic in 1000 ml of RODI should give the same as the 0.1N reagent I had been purchasing through Amazon (before Amazon cut Canada off from this product).

I planned to mix it in a 1L volumetric flask, and to use a 10 ml pipette to measure the muriatic acid. I only have 2 pipettes, a 1000 ul and a 10,000 ul, and I don't use the 10,000 ul (10 ml) one very often, so I decided to test it's accuracy. I set it to 10 ml and pulled some RODI in and expelled it into a 10 ml volumetric flask. The flask overflowed. Hmm, so one of them was off. I figured it was the pipette, so I started fiddling with the setting on the pipette until I arrived at a setting of 9.88 ml to fill the 10 ml volumetric flask to the etched line on it's neck.

I filled the 1 L volumtric flask half full with RODI and pipetted (what I hoped would be) 10 ml of muriatic acid into it. Then I filled the rest of the needed RODI into the 1 L flask and set about doing the normal 4:1 dillution ( 1 L RODI, 250 ml 0.1N) using the newly created 0.1N base reagent.

I added those 2 flasks into my Alkatronic reservoir. There was still about 1/2" of old reagent in the reservoir that was made with the off the shelf 0.1N reagent.

The moment of truth was here. How far off would the reading be? Would it be too far off to be usable? I was already thinking in my head that if it was too far out of whack, I may need to dump the newly mixed 0.1N base reagent and start tweaking the 10 ml of muriatic acid to test other ratios ...

I requested an Extra Measurment from the Alkatroninc and crossed my fingers. :beaming-face-with-smiling-eyes:

Success, or what I consider success! The first measurement was only - 0.5 dKH off from the latest measurment using the off the shelf 0.1N reagent base (2024-11-23 14:00). I did a second extra meaurement to make sure the tubing only contained reagent based on the muriatic and the reading dropped to a spread of - 0.67 dKH. I can live with that.

The readings after the cut over in the above graph show my alkalinity control process start to adjust the flow rate on my CaRx to get the reading back to my target reading of 10 dKH. In case you were wondering why about the increase over the days after the cut over.

For the next time, I plan to use a 100 ml volumetric flask for the muriatic, and mix it into 10 L of RODI. This will give me 10 L of 0.1N reagent and no requirement to buy the OEM 0.1N reagent ever. I had dropped my testing to every 6 hours as I was conserving reagent, but now I can go back to my prefered test every 3 hours again.

I consider the switch over to using the 10N muriatic acid a success. I don't know what I was worried about! ;)

Dennis