Salt test question...

[ta2dwonderwoman]

When I use my drops to do a salt water test I'm wondering if I stop counting as soon as the color changes to something kind of pinkish or do I go ahead and put another drop in and make it go completely brick red? It seems like every time I do the test there comes a point where it changes to a light brick red or pinkish color and then with 1 or 2 more drops it turns dark... Thanks in advance for any advice

 

[JoyfulNoise]

It usually “flashes” from milky yellow to brick red then back to milky yellow. As soon as you get to a point where the milky yellow converts to a pinkish red, that’s the end point. Going to full brick red is over-titrating. You might want to use a larger sample volume. I typically use 20mL and so the titrant drops give 100ppm/drop. The transition is easier to see in my opinion.

 

[chiefwej]

I add drops until there is no further color change. Then subtract that last drop, that made no change.

 

[JoyfulNoise]

I add drops until there is no further color change. Then subtract that last drop, that made no change.

That will tend to over-estimate the chloride ion concentration by 1-2 drops. If the SWG is happy, then it’s not a big deal but you would be reporting a higher salinity than actual.

 

[jblizzle]

I add drops until there is no further color change. Then subtract that last drop, that made no change.

I think the salt test is the only one where this is not the right procedure.

 

[ta2dwonderwoman]

When I do a salt test with a strip it comes up to 5.6 which is 2480 rpm, When I do the drop test it comes up saying 2800... Either way my salt water generator is not working right now and is reporting low salt , I have recently cleaned my plates off so it's definitely not that... I don't know which test to believe...

 

[mknauss]

Believe the higher one. Add enough salt based on it and see if the SWCG starts generating.

 

[ta2dwonderwoman]

Thanks, That was pretty much what I was thinking but I was hoping somebody else would say it so I wouldn't feel like I was in the dark

 

[JoyfulNoise]

Strips are NOT accurate. Best you could expect from them is +/-400ppm. Your K-1766 is a direct chemical measure of the chloride ions in the water. The only reason it has a +/- 200 ppm/drop tolerance is because it uses a 10mL water sample. If you use a 25mL water sample the tolerance is +/- 80 ppm/drop .

Throw the strips out, they are useless.

 

[domct203]

I find that when using the K1766 that when I see the sample turn pink, if I wait a couple of seconds it will fade back to milky yellow, then the next drop will always go brick red, just about every time. That is my endpoint. I go slowly with the drops because of that flash to pink.

This is using a speed stir. If you’re manually swirling the endpoint will be much more difficult to determine.