Mustard Shock and test strips

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T

TimboZero

0
Jul 31, 2011
14
South West France
Opened my pool late this year and was lucky that it hadn’t bloomed.
Whilst trying to shock it with 7litres of 9.6% bleach I found my Aquachek strips showed 5ppm total and 0ppm free chlorine.
So I have added what should have been enough to mustard shock my 48 cubic meter pool.
Still my test strips show the same 5ppm total and 0ppm free chlorine.

At what point do I stop adding shock, could my free chlorine pad on the strips be being bleached out white (the other all show a colour as normal) ?

Many thanks
Timbo
 
We do not trust pool test strips for anything. They are garbage. Invest if one of the recommended test kits if you want to take control of your pool: Test Kits Compared

Then you need to follow the SLAM Process process to clear up the pool and stopping trying to get by with the dump and pray method it appears you are following.

Please add your location to your forum profile.
 
With respect I am not ‘dump and pray’ type, pool calculator said 7litres to shock under the conditions I had.
Been trying to maintain it for 24 hours but with no luck at all.
Yes strips aren’t especially accurate but they are easy and haven’t let me down in 15 years until now.

Logically if the strips were being bleached out it would bleach out all the pads, so....
I can only assume that opening the pool this late in the year has left me with a huge demand for disinfectant which so far I haven’t managed to reach.
Would you tend to agree ?
 
Thanks for filling you your location ... I was guessing you were not in the states ;)

I don't think there is any way you can assume that high chlorine levels will only "bleach out" the chlorine pads ... it will also impact all other pads on the strips.

Here is the problem ... What CYA is your test strip telling you? Given your screen shot it appears that you believe your CYA is 40ppm ... but I know the strip can't tell you that accurately.
Maybe your strip is WAY wrong (we see it all the time) and is much higher than you think and therefore, you are just not raising your FC up high enough.
And then, if you are getting it high enough, how are you able to test multiple times a day to keep it up at that high level?
Answer: you can't.

Then there is the chance that your late opening allowed something like a conversion of your CYA to ammonia resulting in a huge chlorine demand; but no way to verify with test strips.

So, I am kind of at a loss on how to try to help you.
We here similar stories every day ... what I have been doing for years has always worked ... until now.

Yes, opening late can certainly result in conditions in the pool consuming more chlorine
But, I don't think you can even determine that with the test you have available to you.
 
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Click to expand...
 
jblizzle said:
Thanks for filling you your location ... I was guessing you were not in the states ;)

I don't think there is any way you can assume that high chlorine levels will only "bleach out" the chlorine pads ... it will also impact all other pads on the strips.

Here is the problem ... What CYA is your test strip telling you? Given your screen shot it appears that you believe your CYA is 40ppm ... but I know the strip can't tell you that accurately.
Maybe your strip is WAY wrong (we see it all the time) and is much higher than you think and therefore, you are just not raising your FC up high enough.
And then, if you are getting it high enough, how are you able to test multiple times a day to keep it up at that high level?
Answer: you can't.

Then there is the chance that your late opening allowed something like a conversion of your CYA to ammonia resulting in a huge chlorine demand; but no way to verify with test strips.

So, I am kind of at a loss on how to try to help you.
We here similar stories every day ... what I have been doing for years has always worked ... until now.

Yes, opening late can certainly result in conditions in the pool consuming more chlorine
But, I don't think you can even determine that with the test you have available to you.
Click to expand...

Thanks for a more complete response, I hear what you are saying and I know (from past experience) that your first reply covered 90% of new maintainers problems with pool opening.

About 6-7 years ago I had a problem with excess CYA and had to do a drain, since then I have avoided shocking with di/trichlor and hence why I use bleach.
Whilst you are right strips are less accurate, these AquaChek ones are genuinely good and not like the generic , I could do better dipping a toe in , P.O.S. Ones I see everywhere (they get the pH as well as my digital gauge).

Anyhow back to the topic, I agree if the chlorine was high enough to bleach out the free chlorine pad then the others would be white as well. They are not and reading what I’d expect.
So something is eating my chlorine as fast as I add it.
I did notice rather slimy walls, a lot of debris (silt that passes the winter cover) etc in the pool, and since the shock the water has become rather cloudy as if algae is being killed.
 
The pads would not all necessarily turn white from high chlorine, they could be affected in some unknown way.

And regardless of the brand, we just do not trust test strips to be good enough. Granted they might be the best out there, but they are not precise enough and their ranges are too limited.

Not to be too nosy, but do your physical limitations prevent you from adding and counting drops? Let's see if we can come up with something. PM me if you would rather keep information out of the public.
 
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