Might be a silly question....

[Randy Holmes-Farley Verified Community Expert]

They put 50-75% glycol only to dissolve the dye and to have just one bottle? That is crazy.

That's my assumption. I cannot see any other reason for it.

 

[Randy Holmes-Farley Verified Community Expert]

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

I presume the boo is because a single dye is not as good.

 

[biom]

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?

It will work but will be quite inaccurate if just the indicator bottle is poured into the acid. Because adding the indicator into the acid will at first place dilute the acid and on the second place some of the acid will be neutralised by the indicator solution because I assume it is with pH about 8.0- 8.3 (to match typical aquarium water). Also the amount of the indicator will depend on the acid used and might need different calibration of the colorimeter.

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?

I think making DIY RedSea solution will be quite challenging project. Not impossible but there are so many question marks.

 

[biom]

That's my assumption. I cannot see any other reason for it.

I just tried to dissolve Salifert Indicator into their acid and it dissolves quite well no precipitation so far. Maybe they are just making it toxic?

 

[Randy Holmes-Farley Verified Community Expert]

I just tried to dissolve Salifert Indicator into their acid and it dissolves quite well no precipitation so far. Maybe they are just making it toxic?

If solubility of the dye is not the reason, either in the acid or in the salt water it is added to, then I have no idea why they would add organic solvents into the titration fluid.

 

[JimWelsh]

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

It just makes it harder for the human eye to detect the endpoint correctly.

 

[biom]

It just makes it harder for the human eye to detect the endpoint correctly.

Yes that is true, but I don't know how Red Sea did it, but it was even harder to detect the endpoint with the old indicator

old one

new one

 

[Dan_P]

If solubility of the dye is not the reason, either in the acid or in the salt water it is added to, then I have no idea why they would add organic solvents into the titration fluid.

Viscosity increase to make better drops than with a runny solution?

 

[Randy Holmes-Farley Verified Community Expert]

Viscosity increase to make better drops than with a runny solution?

Yes, that's a good point. It also lowers the surface tension, which would decrease the contact angle between the drop and the tip, maybe making it harder to drop loose, which on its face seems undesirable.