0 Alkalinity and 8.0 ph - just installed a new Hayward 3C SWCG

[Weeklyclean]

Brand new pool , i was using chlorinating pucks in the skimmer temporarily ( SWCG was on backorder) and took the following readings:
June 11 : FC 7.0, PH 7.7, TA 60
June 14 : FC 2.3, PH 7.8, TA 47 (puck had completely disolved)
June 23: FC 7.0, PH 7.8,, TA 36 (had added a puck every 2 -3 days after they dissolved)
Water was christal clear
Then installed the new Hayward Salt and Swim 3C SWCG two days ago and PB set it to level 5 (30 mn chlorination active per hour). Salt is at 3300 ppm
(the Hayward 3C just has levels of chlorination that you set with + and - settings)
I just took a reading today (puck was removed at SWCG install)
July 1st : FC 18.47, PH 7.6, TA 0.
Dont know what is wrong. I am using the Lamotte Colorx and using test strips and they both concord. (TA is pale green on test strip which is equivalent or close to 0)
How can you have a PH of 7.6 while TA is 0 ? Puzzled (notwithstanding the huge amount of FC)
I just reduced the SWCG chlorinating level to 2 which reduced chlorination to 12 mn per hour while pump is running.
TA = 0 is off the charts ? what to do with this and the 7.6 PH

 

[mknauss]

The TA cannot be 0 with a pH of 7.6. The test equipment you have is not all that accurate.

At your setting of 12 min/hour your SWCG is making 3 ppm FC per day. A good level but with out a CYA have no idea what your target FC should be.

 

[mgtfp]

Not sure how the ColorQ and your test strips work. If your FC really is over 18, then both, pH and TA test, might not work anymore, many indicator chemicals get bleached out at these levels, probably also applied to strips and the ColorQ.

And yes, in buffered water, pH 7.6 and TA 0 is chemically impossible. At TA 0, pH would have to be 4.5.

 

[Weeklyclean]

Thanks for the replies. The CYA level was 29 when I took the latest measurements (CYA acquired from the pucks i used temporarily)
Yes best thought is the FC of 18 ppm could be the cause of those misreadings in TA and maybe PH.
I will do tests this week end and see what are the levels after reducing the Salt and Swim 3C at 2.
I am not going to try to add chemicals to adjust TA or PH for now before new tests.
Thanks

 

[Weeklyclean]

Re tested today after lowering the Salt and Swim to level 2.
Here are the results :
FC is still out of range at 14 ppm (TC 14.5)
CYA is 29
PH 7.5
TA 0
CA 171
Salt 3200 ppm

This pool seems to be a chlorine keeper as FC is still hanging there at that high level after 3 days of using the new SWCG. (Please note that prior to SWCG I was placing a puck in the skimmer every 2 or 3 days per the PB advice and this must have brought the FC up, so I think , if you do not have a SWCG , better use bleach or a Chlorine dispenser and monitor Chlorine before adding).
So I decided to shut down the pump and SWCG and will wait until the FC drops.
As mgtfp said, many internet docs I just checked say that out of range FC levels can actually bleach the TA test chemical. It will render it yellow, which explains the TA = 0 result showing on both the digital test and the strip.
I will monitor and update when FC gets back to normal levels with help of some great sunshine, though weather is a bit chilly today at 60 F.

 

[mknauss]

You need a proper test kit. I suggest the TF-100 or Taylor K2006C. A proper test kit is needed to get the accurate water chemistry results needed to follow the TFP protocols.