Might be a silly question....
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Randy Holmes-Farley
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I'm not aware of what concentration of acid they use.
Randy Holmes-Farley
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It is likely a dilute sulfuric acid or hydrochloric acid. In an alk test it doesn't matter which, just the concentration.
The only other things needed for an alkalinity titration is a measure of pH, either by pH meter or an indicator dye (or mixture of dyes).
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Japtastic
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Thanks, Randy. Yes, you are right. So could I make it myself with Mono Ethylene Glycol and Hydrochloric Acid?
Also I guess this part is important as we don't know what the other 25% is.
There are no additional ingredients present which, within the current knowledge of the supplier and in the concentrations applicable, are classified as hazardous to health or the environment and hence require reporting in this section.
Also I guess this part is important as we don't know what the other 25% is.
There are no additional ingredients present which, within the current knowledge of the supplier and in the concentrations applicable, are classified as hazardous to health or the environment and hence require reporting in this section.
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Randy Holmes-Farley
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The glycol is there to help dissolve the dye. It is not really needed otherwise in an alk test.
Randy Holmes-Farley
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Is the dye in a separate solution that you are not trying to DIY?
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Look up bromocresol green. Looking at its color vs pH, ny hunch is that will behave like the Red Sea pH indicator part. (I haven't tried it though)
Randy Holmes-Farley
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I think some alk tests use a mix of more than one dye to get a sharper color change at the needed pH.
Bromophenyl blue and bromocresol green, I’ve heard. I’ve just used phenolphthalein at work.
Methyl red and bromocresol green. But, it appears that Red Sea switched to just bromocresol green some time ago (BOOO!).
Phenolphthalein is for titrations of acids by bases, with an endpoint of 8.2. Totally different.
They use that mixture of bromocresol green and methyl red, I believe. Hach also uses this mixture: https://mena.hach.com/bromcresol-gr...tor-solution-100ml-mdb/product?id=25142847599
The mixed indicator is intended to produce a sharper endpoint for the human eye to detect. Pure bromocresol green makes a better indicator for a colorimetic titration, IMHO.
I cover the correct endpoint color of the Salifert (bromocresol green / methyl red) method ad nauseum here: https://www.reef2reef.com/threads/alkalinity-titration-endpoint-ph-salifert-endpoint-color.543556/
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Japtastic
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Thanks all, this is all great info. The Red Sea bottle comes as a clear orange liquid so it definitely looks like one of these chemicals. Sure would be good not to pay $25 for 50ml of it every month or so.
I could buy Salifert at half the price but this comes in two bottles and I don’t have room in my Reefbot for the extra bottle. Hence the reason for using Red Sea with its one bottle.
I'm a bit confused about the last few comments, do these relate to Red Sea or Salifert? The Red Sea bottle starts as Orange then turns blue as you add tank water, you look for the change to green for the end point and if it turns yellow you have gone too far.
I could buy Salifert at half the price but this comes in two bottles and I don’t have room in my Reefbot for the extra bottle. Hence the reason for using Red Sea with its one bottle.
I'm a bit confused about the last few comments, do these relate to Red Sea or Salifert? The Red Sea bottle starts as Orange then turns blue as you add tank water, you look for the change to green for the end point and if it turns yellow you have gone too far.
biom
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Sorry, yes the last few comments are for Salifert.
Not sure if the indicator of Salifert could be added directly to the acid and to have only one bottle, but it could be the reason why RedSea added 50-75% glycol in their solution.
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Japtastic
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Thanks. I imagine Salifert would have gone the one-bottle route if possible so I'm guessing adding the two bottles together wouldn't work?
So I'm still a bit lost on how I can (if at all) try to DIY this Red Sea solution. Can I just get some Bromocresol Green and MEG? Also why the BOOO! about the BG @JimWelsh
So I'm still a bit lost on how I can (if at all) try to DIY this Red Sea solution. Can I just get some Bromocresol Green and MEG? Also why the BOOO! about the BG @JimWelsh
