Something doesn't add up

[MarkHoop]

Something isn't making sense to me here..

I made Borax (Mule Team 20) and liquid chlorine additions and my FC went down and my pH went down.

Doesn't make sense....help??

 

[MarkHoop]

Only thing I did yesterday was start the heater to get it to 75 from 72

 

[MarkHoop]

I made previous Cl additions with the same jug and it reacted as expected

 

[mknauss]

The borax would have raised the pH 0.1. So really hard to say at those small variances.

The FC likely is getting consumed by organics. Do an OCLT.

 

[MarkHoop]

Did I miscalculate the Borax. I have ~ 0.77g/ml so I added 900ml (graduated pitcher) when I needed about 600g by PM? Pool is a little cloudy so agreed that CL may be getting eaten up but didn't expect pH to drop like that?

 

[mknauss]

Poolmath shows you added 690 gms of borax to a 22000 gallon pool. That will raise the pH by 0.1.

Either way, there is no need to raise the pH. Your TA of 70 will let the pH be stable or rise a bit. So leave it.

 

[MarkHoop]

Ok, I will bring the FC up with a liquid Cl addition and go from there. But for the record will organics effect FC like I am seeing?

 

[mknauss]

Organics consume FC. Rapidly. So add enough liquid chlorine to get to at least 10 ppm this evening, circulate for a good hour, test FC, then test FC again in the am before sun hits the pool surface. That is an OCLT.

 

[MarkHoop]

Organics consume FC. Rapidly. So add enough liquid chlorine to get to at least 10 ppm this evening, circulate for a good hour, test FC, then test FC again in the am before sun hits the pool surface. That is an OCLT.

Ok, so ran my OCLT and it looks like I am good. No drop in FC and my pH also returned to the levels I expected (would love to understand that part??). Again, another TFP success

 

[MarkHoop]

Ok, so ran my OCLT and it looks like I am good. No drop in FC and my pH also returned to the levels I expected (would love to understand that part??). Again, another TFP success

Can any of the experts help me understand the pH change? It is accurate as I tested twice both days