CH and TDS are high, but CSI is OK - should I worry?

[tfoggo]

Hi there.

My pool water CH and TDS always seem very high: today, CH=920, TDS=2,310.

Combined with other measurements (see below) PoolMath shows the water CSI as 'balanced', and the water itself remains clear and sparkling (having learned how to look after it from you guys!). So no problems affecting enjoyable swimming. Just wondering whether I should be concerned about these two seemingly 'out of whack' readings and whether there's anything I should be doing about it. Or is the 'swim test' the 'best test'?!

Today's readings:
TA=50
pH=7.5
CH=920
CYA=40
FC=3 (I'm about to raise it to 6 and will bring pH down first)
TC=3.2
TDS=2,310
Temp=26C/79F

All the best.

 

[mknauss]

What is the CSI value?

The TDS is meaningless.

You are close on CH to not being able to keep your CSI in the OK range. But by having such a low TA and managing your pH you are OK now.

Be aware that water temperature effects the CSI too. So this winter, you may have trouble.

Take care.

 

[duraleigh]

TDS is irrelevant. CH may cause some problems......what is the CH of your fill water? How do you chlorinate?

 

[tfoggo]

What is the CSI value?

The TDS is meaningless.

You are close on CH to not being able to keep your CSI in the OK range. But by having such a low TA and managing your pH you are OK now.

Be aware that water temperature effects the CSI too. So this winter, you may have trouble.

Take care.

Thanks for the advice - much appreciated.

- - - Updated - - -

Oh, and CSI value is -0.04.

 

[tfoggo]

TDS is irrelevant. CH may cause some problems......what is the CH of your fill water? How do you chlorinate?

Many thanks for the response.

So I really shouldn't bother measuring (and worrying about) TDS?

CH of fill water was 300 last time I tested it (a year ago).

I chlorinate with 15% liquid chlorine.

All the best.

 

[duraleigh]

Not sure of the price of water over there but you would be wise to drain about 1/2 or a little more of that pool and get your CH down to a more manageable 4-500. Since you are refilling with 300 CH water, It will start to slowly come back up so you could plan on a drain every couple of years.

That drain will also lower your TDS but, again, it is not really relevant.

Keeping your TA and pH right around where they are (no higher) will insure you against calcium scale and, with an occasional partial drain, a TROUBLEFREE pool!

 

[tfoggo]

Thanks again. I'll drain and refill at the next opportunity (the British weather's being unusually good to us at the moment so every minute of swim time is precious!).

I find TA and pH easy to control (ever since switching to the TFP methodology and ditching all those complicated 'water balancers'!) and always keep an eye on the overall CSI to ensure I don't stray in to scaling territory: my air source heat pump is particularly sensitive to scaling apparently.

All the best.