Ascorbic Acid (AA) treatment with 90% water exchange

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needsajet

needsajet

TFP Expert
LifeTime Supporter
Jan 4, 2016
5,392
Sydney, NSW, Australia
Pool Size
44000
Surface
Plaster
Chlorine
Salt Water Generator
This is expensive! My budget is at AU$440 ($US299)

Do you all reckon I can get away with no sequestrant if I initiate the draining as soon as stains are lifted?

Differential draining water exchange will take around 36 hours to remove the old pool water. I am also leaving polyquat out for budget purposes, but can't see algae becoming an issue in 14C 57F water
 
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It's winter there. I doubt you will get algae issues. I have done AA and an exchange in our pool in winter and no issues.
 
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Texas Splash said:
I would agree that algae shouldn't be an issue. What about the new water? You sure it's going to be metal-free? What caused the staining to begin with?
Click to expand...
I'm 99% sure it's the salt. There's no iron to speak of in our city water, and there was no sign of stains for the first six years after building the pool.

A lot of people here told me they just dump salt in, do nothing, and just let it dissolve. I had always (and still always) brush it around as it dissolves, even if just every 10 or 15 minutes. One time, I bought the highest grade over-priced salt, and just dumped it on my ledge and let it dissolve without moving it around, to find out. After it dissolved there was an iron stain the shape of the heap of salt, which I was able to remove with AA in a sock. Hence why I'm pretty sure the 0.5% impurity of the salt is partly iron, and the iron accumulates over time.

I did the AA a few years ago, then monthly HEDP sequestrant, which all worked. The speed the iron stains disappear is amazing. But that sequestrant adds up to more than $400 per year, so I'm going to try the water exchange.

The stains are localized in areas of low circulation (e.g. back edge of steps) and high circulation (e.g. skimmer throat), so it's not terrible or anything, just bad enough that it bugs me.

Iron stain 1.jpg
 
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Are you doing a no drain water exchange or a drain/refill?
Unless you have a high water table, I would think a drain/refill would be quicker, less costly (water wise and produce better results.

Several months ago, I help my neighbor do an ascorbic acid treatment on her white plaster pool. I was amazed at how quickly the treatment worked. Full drain/refill immediately after, which also took care of the high CH and CYA. No worry of high water table here.
 
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Hey Gene, yeh, I've decided to do a no-drain-water-exchange, very much part of my own learning.

Almost 50% swapped so far. Looking forward to seeing how it goes. I used the TFP calculation (kudos to whoever did that) and got -26 so it's a fairly strong salty/fresh layer. Fingers crossed. The wastewater is at 3600 ppm salt. I forgot to pre-test my salt, but as of 21 days ago, it was 3900
 
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