Strange blobs in CH test vial?

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anonapersona

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Nov 5, 2008
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I did the CH test yesterday and at about the point where I expected the color to turn, instead I noticed little blobs of pink swirling around. I did it again, same result. Instead of something like 240, it turned at 320, but I have not been adding calcium via cal-hypo for several weeks, or hardly ever, maybe once. Tried again today but got the same result.

Any chance the reagents are temp sensitive? It is about 99 degrees out there right now. Both times I was doing test outside, not in the house like I typically do. The reagents are stored in the house, so should not have warmed up so much.

Maybe I was hurrying because of the mosquitoes. I was trying to wait long enough between drops though sometimes they do tend to drip out on their own schedule. Could wait time be it?

Otherwise, could calcium rise as rocks in the waterfall wear down? I get a lot of sand from the waterfall and I suspect that adding acid to lower TA could be increasing that wear. Would acid leach calcium from sandstone?
 
I have no idea what to tell you about blobs of pink, but I can tell you when I was having issues with the CH test waterbear told me another way to do it which helped me verify which reading was right. here are his instructions:

with high CH you can do the test this way--10 ml water sample, 10 drops of first reagent, 3 drops of indicator, and then when you titrate each drop of titrant is 25 ppm CH instead of 10 ppm. You lose some precision but when you have very high calcium like yours it really does not matter that much if your CH is 620, 625, or 630 ppm (or even 600 or 650!)
 
floaties often appear for a few reason. When you add the first reagent (calcium buffer) be sure to swirl very thoroughly since the purpose of this step is to precipitate magnesium. You want to make sure this is complete before you add the indicator.
Also, if you rush the test and do not mix completely after each drop you are more likely to have floaties.
If for no other reason a magnetic stirrer is worth it's weight in gold for this particular test. It really speeds it up. If you have high calcium and you are doing the high resolution test where each drop is 10 ppm AND you are doing this test properly it can take quite a while to do. Do the math, 30 seconds swirling after each drop and 40 drops for 400 ppm calcium is 20 minutes plus however long it took to put in the 20 drops of buffer and the the indicator so we are close to half an hour for about 400 ppm CH!
With a magnetic stirrer you can complete the test in about 2-3 minutes with the same CH level!
 
How about if I put the cap on and shake the whole thing? That's as good as a stirrer -- right?

Secondly -- magnesium.... I was spraying the plants near the pool with fertilizers recently, perhaps some dripped off the leaves. I was using epsom salts as well (magnesium sulphate).
 
anonapersona said:
How about if I put the cap on and shake the whole thing? That's as good as a stirrer -- right?
Nope, you are introducing air and that will disrupt the pH. For Calcium hardness the pH has to be at a specific point or you are also measuing magnesium hardness. That is why it is swirled and not shaken. There is no way around it if you want accurate results. Sorry!
Secondly -- magnesium.... I was spraying the plants near the pool with fertilizers recently, perhaps some dripped off the leaves. I was using epsom salts as well (magnesium sulphate).
Click to expand...
Magnesium is a normal part of water hardness. Total hardness is the sum of the calcum and magnesium hardness expresses as calcium carbonate.
To get calcium hardness the magnesium in the water needs to be precipitated since the calcium indocator complexes much more strongly with magnesium than calcium.
To get magnesium hardness you subtract the calcium hardness from the total hardness.
Depending on your geographic location magnesium may contribute only a little or a great amount to the total hardness of the water.
 
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