Perfect Ph with low TA, but then ...

[TxCoolGuy]

Just wanted to know what you think about this?

For the last month or so I've been testing my C and Ph pretty regularly, but I put off a more in-depth TF100 work up. My C has been running 4-5 and my Ph has been a rock-solid 7.3-5.

I finally got around to checking my TA and CH, and TA was quite low- around 10. CH was about 275.

My pool was taking almost NO acid to keep at 7.3-5 with a low TA. But, going by the guidelines I worked to bring TA up to 50 (as a first step to 60-70) and let it settle for a few days. I did not adjust my dispenser settings, and left it where it was. With the new TA my Ph is now at least 7.8, if not 8.0+. I was out of town for 2 days, so I just put some acid in it this morning and dialed up the dispenser.

I'm surprised with almost no TA I had consistent good Ph with almost no acid input. Now that my TA is higher, I'm going to be running through acid at a much faster rate. What's up with that?

Thanks for any insight that can be offered!

 

[mknauss]

I would question the low TA test result. Chemistry tells us a TA that low would have unstable pH. Your most likely high TA and pH fill water may play a factor, but TA near 0 will not support a stable pH in the 7's.

 

[Jimrahbe]

I just want to make sure we are all on the same page... What do you mean you "Dialed up the dispenser"...

Thanks,

Jim R.

 

[TxCoolGuy]

I did test the TA several times to ensure it wasn't a single bad reading. It's possible my TF100 chemicals are past their shelf life. I'm going to test again in a moment to see where I'm at. I'll return with those readings.

"Dialing up the dispenser" is referring to adjusting the IntellPH acid dispenser to a higher value. In this case, I was at 15% and I've moved it up to 30%. It will put more acid into the pool during the pump's runtime, now.

I think I'm going to go test again ...be back soon!

 

[TxCoolGuy]

Back from the test..

TA reads 70 now (turned red on the last drop, so 70? maybe 60)

Ph is reading 7.9. That's with my calibrated meter. My earlier reading this morning was based on the drop test/color match. Ph was redder than the scale with that method.

 

[Jimrahbe]

Sorry, I missed that you had a acid feeder..

Jim R.

 

[TxCoolGuy]

With the TA reading at 70, my course of action now is to balance the Ph and dial in the dispenser. I'm not sure what was happening before with the low TA, but the test readings seemed to be accurate. I was manually putting in some acid as part of cleaning calcium build up off of spillway rocks, so that must have had more of a positive affect than I realized.

Thanks for your comments, guys!

 

[jblizzle]

Make sure you are always adding drops until the last one causes no further color change and don't count that one.

 

[Teald024]

Why are you trying to drive pH down to 7.3? You would use less acid, slower drop of TA if you only pushed down to 7.6

 

[Vegas Mike]

Is the TA level only important as a buffer to keep pH stable? If that is true, then if you have a stable / manageable pH the TA would seem irrelevant. Assuming a southwestern, plaster pool where your municipal water is pH 8.