High free chlorine levels

[Qphan79]

pH test is invalid with FC above 10 ppm.

I see...so even if I lower the FC with a chlorine neutralizer, would that allow me to get an accurate pH test result? But lowering the FC below 15 would also mean I run into sterility issues, correct?

 

[Qphan79]

I’m going to just go ahead and start draining tomorrow. Haven’t had to do it in the time I’ve owned this house so I’m sure it’s much overdue. I’m just hoping there’s enough time to then fill it and balance out the water chemistry by this weekend! Thank you for all of your help!

 

[jblizzle]

The water does not get old like you implied and require drainingsThe only reasons to drain are if you let the CYA get too high, like you have, or if the CH gets very high.

Your previous post was correct, which is one reason we do not recommend having the CYA that high

 

[Qphan79]

The water does not get old like you implied and require drainingsThe only reasons to drain are if you let the CYA get too high, like you have, or if the CH gets very high.

Your previous post was correct, which is one reason we do not recommend having the CYA that high

Yes, I meant that I was overdue for draining since CYA has been building up over the whole time. Obviously I’ll need to keep tabs on my CYA level in the future, but essentially I will always need to at least partially drain every once in a while to keep CYA from getting to high? Or should I alternate chlorine tabs with liquid chlorine to reduce the amount of stabilizer being left behind by the tabs?

 

[mknauss]

Or should I alternate chlorine tabs with liquid chlorine to reduce the amount of stabilizer being left behind by the tabs?

That statement is correct. Use liquid chlorine for daily maintenance when you are home. When you leave for more than a couple days use trichlor tablets in a floating dispenser. Maintain your FC based on your CYA level.

 

[Qphan79]

Got it, I appreciate the help! Cost-wise, is liquid chlorine more or about the same compared to the amount you get from a tablet?

 

[mknauss]

Most chlorinating methods are the same cost when everything is taken into account. With tablets, you need to account for the baking soda you will be using to combat the acidic nature of the tablet and also the water cost to drain a 1/3 to 1/2 your pool volume every couple months to reduce your CYA.

 

[Qphan79]

I just like tablets for the convenience but I didn’t realize until now the cons of using them!

 

[Qphan79]

So it took several hours to drain the pool down to roughly 1/4 or maybe closer to 1/5. Then another 12 hours to fill it back up! Here are the current readings:
FC: 17
pH: 7.5 (I realize that this may not be accurate based on prior discussion)
Ch: 400
TA: 140
CYA: ~70-80
I’m thinking my prior CYA levels were even higher than I realized since I only did a half dilution. I guess I will have to do another partial drain again or just stop using chlorine tabs for the time being. But I think I’m just going to go with the current water for this weekends pool party.

 

[ajw22]

A FC of 9-11 will do for a CYA of 80. Let your FC drift down to 9 and then check your pH.

A FC of 17 with CYA 80 is fine to swim in.

Enjoy the pool party.

 

[Qphan79]

How long are we talking for FC to drift based on the CYA levels? Are we talking several days most likely?

 

[Mr Bruce]

Most pools lose 2-4 ppm FC per day based on use, sun, etc.

 

[jblizzle]

The above is true when the chlorine is at normal levels for your cya. But when that FC is quite High you will lose more per day. You might lose 30 to 40% each day

 

[BilScott]

Thank you