Chem Geek or Mbar - are you there? Iron test question.

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Originally Posted by labdi01

My only concern about my numbers from the Taylor test is there were 2 incidents where the color they described was not the color I got - but adding more reagent didn't make a diff. Example - in the TA test, my color was supposed to change from green to red. I got more of a magenta. The calcium test said solution should turn blue. I had more of a indigo/purple.

With a CYA of 50 - I removed the CYA sock from the pool (this am pool store told me my CYA was 100 - but I did Taylor twice and got 40 and 50 respectively).

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For what it's worth, the color palette you describe for the end-point of the Total Alkalinity (TA) and Calcium Hardness (CH) tests match that of my testing.

TA test titration ends in a dark magenta (not red)

See http://gizmodo.com/assets/resources/2007/11/magenta.jpg

CH test titration ends in indigo / lavender (not blue)

(I'm not aware of any particular reason for these discrepancies and have tried performing the tests in every way recommended by Taylor and others, but the results are invariable and have been for 3 years.)

Thank you so much Polyvue!

I doubted myself more than the test.

Thanks Chem Geek!

Although that makes complete sense to me that the iron test would measure sequestered ions, what I'm not understanding (and please pardon my pool/chem ignorance) is how my iron tests went from 0.5 in the days following (6 quarts of) sequestrants. Then we shocked, turned back to brown, filtered to clear, then iron was down to 0. Then suddenly, iron went up to 5 (in 48 hrs - from 0) without adding so much as 1/2" of water. I would think for that to happen in a 13.5K gal pool, I would have seen sludge come out of the hose and I didn't, nor did I get any staining with that top-off.

That's an easy one to answer. The pool store likely screwed up one of the iron tests would be my guess. Happened with mine also

Question is - which do I believe?

My advice is to look at your pool - if it looks good, don't worry about it:) After many years of trying to find out where the metals were coming from, and how to get them out of my water, I came to the conclusion that I would deal with the stains as they come. I hate stains, and I am not a chemist like chemgeek. I just give the benefit of my experience. Now I just enjoy my pool and deal with the dreaded stains if and when they come

You're right mbar! Thank you so much for sharing your wisdom with me! It's greatly appreciated.

Right now, I have the pool at shock level to rid a high CC (and I seem to be winning). I have liner stains as well, and they're driving me crazy - because from a distance, it makes my pool look green (liner is blue and white with an alligator-skin pattern) and I feel like I worked too long and hard to get the pool in shape to be left with it looking any less than perfect. ;oP

Should I hold off on an ascorbic acid treatment after just fighting off a potential bloom and wait for the pool to be stable for a little bit?

Yes hold off. I would get the chlorine to hold steady overnight. Keep the ph low at about 7.2 - when you are finished shocking and the chlorine is holding, then add more sequestering agent. This should take care of the staining. If it does not - then just add a small amount of ascorbic - just a cup or so around the sides of the pool, and put the pool on circulate for a couple of hours. This should do it, you should not have to do a full treatment. The small amount of ascorbic should work without having to rebalance the whole pool again. It will take down the ph so just make sure it does not go under 7.0. When you get to this point it is just a matter of tweaking the water to get the right amount of sequestering agent to keep the stains away.:)

Will do mbar!!! Thank you so much! I've come a long way since I took that cover off - and I certainly couldn't have done it without the great people on Pool Forum. I've already learned so much (but what I don't know still could fill a warehouse, I'm sure!).

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Originally Posted by mbar

I am not a chemist like chemgeek.

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Just for the record...I'm not a chemist either, don't have a PhD in chemistry, don't work in the industry, etc. I did major in physics & chemistry at Cal Berkeley (field major in physical sciences since they didn't allow a double major in those two due to too many overlapping courses, mostly in math). I rekindled my interest in chemistry when I got my pool 7 years ago and ran into problems when using Trichlor tab/pucks. Did some chemical research and found The PoolForum.

I totally agree with Marie that if the water is clear and there is no staining, then don't worry about the varying metal measurements -- at least one of them is wrong. The 5 ppm sounds suspiciously high, even if sequestered.

Richard