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Stains on pool liner

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Hi everyone


We have previously had stains on our pool steps (fibre-glass) which eventually just seem to disappear throughout the summer.


This year, however, we now also have stains appearing at the bottom of the pool on the pool liner.   The stains will not brush away.   I am not sure if they are the same kind of stains as are on the pool steps.   I tried brushing a lemon over them but nothing happened.   Have also shocked the pool, ditto.     The stains are brownish in colour although in some lights they look darker, almost blue - its quite hard to see as they are on bottom of pool.   Stains on steps are light brown.

Water test results as follows (yes, I am sorry, we do use tester strips ..... )


Total hardness - 100

total chlorine - 2

Free chlorine - 3

pH - 6.5 (pH is always low in the pool, has always been low, seems impossible to raise it very much)

Total alkalinity - 40

Cyanuric acid - showing zero (!)


We use multi-chlor tablets from the local pool shop.


Can anyone suggest next steps to try and resolve problem please?


Many thanks

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No ideas anyone?

I know I am completely useless at the pool thing - OH is now outside in rain staring despondently at bottom of pool waiting for me to give him instruction as to what to do .... he will be waiting quite some time .....


Sorry, just at a loss as to what to do first ... thinking add something to increase total hardness (is it anti-calcaire?), then bring pH up some, and then see what happens? Probably wrong - have spent all day reading and cannot get my head around it - and that from a former bio-chemist - shame on me.



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I can help, you need to get rid of the test strips, it is impossible to have total chlor at 2 and free chlor at 3, if you use multi action your CYA cannot be zero so you need accurate testing.

The stain issue I have mentioned on your other post.
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Thank you - yes, I am (finally) coming to the same conclusion myself. I have been looking at different testing kits - could you recommend the kind of tester I should be using, as there are so many and as you can see I am not great at pool-related things.


Many thanks

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La Motte colour Q7

PM me for details on where to get it.

If you don't invest in good test equipment then you will never get to know what is going on with your water chemistry and any sort of diagnostic will be impossible - or guesswork.


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