Ph rises overnight

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az240z

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May 1, 2016
74
Glendale, Az
Last nite I did a test for FC and Ph. The resultys were

Ph 8.2+
FC 2

I added the necessary MA and Cl and retested

PH 7.8
FC 6.5

This morning after running the pump all night I got the following

PH 8.2
FC 5

I lose 75% fc during the day. Is the continuous high PH causing this? I will be doing a full test tonight..
 
Yeah - do the full tests. CYA too.

My guess is TA is really high which drives up pH.

And you shouldn't be losing 1.5 ppm FC overnight either. That's an indicator that something else (algae?) is probably going on.

ETA - you beat me to it.
 
Your TA is a bit high and pH of 7.8 is on the upper end of the recommended scale too. Try pushing your pH down to 7.4 and see if you can keep it around 7.4 to 7.6, if you do that the TA should come down in time, I keep my TA in the 60 to 80 range and pH seems to be much more controllable. If you want to actively push the TA down there is a link in pool school with a process to do that.

Also a FC loss of 1.5ppm over night could be a concern you might have something growing in the water take a look at the SLAM process in pool school and look at the OCLT test criteria. You might want to preform the OCLT test tonight just to be sure things are as they should be.
 
That TA is high enough to drive pH up quickly.

Work this plan: http://www.troublefreepool.com/content/129-how-to-lower-lowering-total-alkalinity

My pool is way happier with a TA around 70. pH hovers around 7.5-7.6. The TA will rise throughout the summer with our high TA fill water. I had my down to 70 in April and by last weekend it was up to 90. So I used the process linked above to get it back down to 70.

You should also run another OCLT tonight and be prepared to SLAM. http://www.troublefreepool.com/content/136-perform-the-overnight-fc-chlorine-loss-test-oclt Losing 75% of FC daily and 1.5 ppm overnight likely means something is consuming your FC.

And I would prioritize the OCLT and FC issue over the TA.

ETA: And now someone else beat me to it...
 
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Thanks for all the suggestions. I can't slam until Sunday as company is coming for the weekend. I know some slams should take 3 days, so I may put it off till next Friday when I have 3 days to test.. I will start the TA tonight..
 
Many SLAMs take longer than 3 days too. I think mine took 8 or 9 days.

Keep the FC on the high end until the weekend. Couldn't hurt - and you certainly don't want it to turn green or run out of FC and potentially have other nasties in the water.
 
az240z said:
Thanks for all the suggestions. I can't slam until Sunday as company is coming for the weekend. I know some slams should take 3 days, so I may put it off till next Friday when I have 3 days to test.. I will start the TA tonight..
Click to expand...
I'd worry more about the falling FC than the rising pH. You don't want a cloudy and/or green pool for your guests. Drop pH to 7.2 and raise FC to 24 as soon as you can. You might be able to stop an algae bloom before its starts.
 
I like your aerator. What did you do? Hook a vacuum hose into a return line and reduce the other end into a garden hose?

And by the way, your aerator didn't lower the TA. The acid (or whatever you used) lowered both the pH and TA. Then the aerator raised the pH w/o causing TA to come back up.
 
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