Stabilizing PH

[Papahemi]

I have recently switched to the TFP method and I am having a little trouble getting the PH to stabilize. My readings yesterday were as follows:
FC-2
CC-0
PH-7.5
TA-110
CH-265
CYA-40

Added 65 OZ of 10% Liquid chlorine

Today readings
FC-5.5
CC-0
PH-7.0
TA-110
CH-265
CYA-40

Action:
Aerating for 30 min using sheer descent waterfall

FC-5.5
CC-0
PH-7.8
TA-110
CH-265
CYA-40

This has been going on for a week. With the only chemical addition to the pool is 10% chlorine. Pool is crystal clear with no other problems. PH goes down to 7.0 or lower then comes back up to 7.8-8.0 with aeration. Cycle then repeats. I am hesitant to add additional chemicals until a fully understand what is happening. Using Pool Math my CSI is within range.

 

[JoyfulNoise]

Your TA is too high. Keep adding acid and aerating until you can lower it. Take it down to 80ppm to see if that helps. Go lower as needed. Do not go lower than 50ppm.

Check your fill water. If it has high TA and you experience a lot of evaporation, you may need to consider controlling your evaporation rate to keep the addition of fill water low.

 

[woodyp]

Aeration naturally raises the PH. The more water surface being broken--the faster it rises.

 

[Texas Splash]

Papahemi, Matt is explaining the technique for lowering TA in an effort to help keep pH low. But when I read your question, I get the feeling you are saying your pH "drops" more than you want it to. Or am I just mis-reading your scenario?

 

[Papahemi]

The PH is dropping without the addition of acid. PH drops to 7.0 then brought back up with aeration then drops again to 7.0.

 

[Texas Splash]

That's what I thought. Usually it's the other way around. Well, consider yourself somewhat fortunate I guess and continue to use natural aeration to your advantage. I'd be hesitant to increase TA at this point until the pool settle-in more later in the season. It may be an option later though. But definitely watch pH as you have been since too low is very corrosive. You're doing great by watching it.

 

[JoyfulNoise]

The PH is dropping without the addition of acid. PH drops to 7.0 then brought back up with aeration then drops again to 7.0.

Not to sound like Capt Obvious, but are you sure you're adding chlorine and not acid?

Given your parameters I don't see how your water could drop that far in pH.

 

[duraleigh]

Given your parameters I don't see how your water could drop that far in pH.

+1 what Matt is saying. something else is going on with testing error or some other variable.

 

[woodyp]

Got any pucks in a floater some where?

 

[Papahemi]

No pucks will ever enter this pool again. Too many CYA problems in the past. Walmart Pool 10% liquid is the only chlorine I use.

 

[Papahemi]

Just tested City water for TA. Got color change from green to slight red at 20. Full bright red at 30. Retested PH with new supply of regent R-0004. Reading 7.8-8-0. I will retest again tomorrow and post results. Thanks to all.

 

[Papahemi]

Here are this mornings Test reading:
FC-3.0
PH-7.0
TA-105
CH-265
CYA-40

Turned on aeration for only five minutes to test amount of PH rise and PH went to 7.8 to 8.0. How is it possible that the PH can rise that fast in 17000 gallons of water? Does water stratify at different PH levels? Should I circulate the water before testing? I should also report that this PH swing from low to high to low to high was done without any chemical addition including 10% liquid chlorine.

 

[Texas Splash]

Rather than focusing on the pH itself changing in only 5 minutes in a 17K pool, I would suspect there may be a bit of inconsistency in the body of water and that (yes) circulation would be ideal - perhaps 15-20 minutes of mixing prior to obtaining your sample.

 

[Papahemi]

Here is what I have done and observed during the past week. I test in the evening around 6:00 PM about one hour after the filter cycle begins and make any additions at that time allowing the 8 hour filter cycle to disperse additions.. I now draw my water sample using the Taylor 2006 FAS/DPD test kit vial directly from the pool at different locations each day ( I was using a small plastic collection bottle. Did this make a difference, I doubt it). First day reading was 8.0 so using Pool Math I added acid to adjusted to 7.6. Tested the next day at same time,same method and PH was 7.4. Thought to myself why was it not closer to 7.6? Remeasured my pool and recalculated size and discovered my pool was 4000 Gal. less than my PB told me (adjusted my Poolmath). The PH pretty much stayed at 7.4 for the next couple of days. The FC dropped a little under 2 ppm each day so I am adding daily 10% to keep FC at 5 ppm with no indication of CC. TA still a little high at 110 ppm. CH still on low side at 270. Tested yesterday for Phosphates and got ZERO reading. On Monday I am having a new Intellipro VS 2 pump installed and I am converting to SWG with an Intellichlor IC40. Checking the TFP pool math I will have to get the TA down some more and the CH up some more. CYA is now at 40-50 ppm. After I have the work accomplish I will be working to bring all readings to TFP pool math levels. My CSI has always been within the Pool Math range. My thanks to all. Stay tuned more to come