Can't keep my pH down

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Fiveflat

Fiveflat

Well-known member
Apr 8, 2021
54
Herald, CA
Pool Size
18000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I'm constantly in a battle with my pool trying to keep pH down (for the last two weeks lol)
I'm adding muriatic acid according to poolmath and it still always creeps up to 8.2+
(Scale only goes up to 8.2 but if I were to guess, I'd say 8.6)
I have to run my spillway to get the water into my spa so I'm guessing that aeration is the cause of this.
Without having any experience with MA to begin with, how often should I expect to have to add it?

Now my numbers are slightly off but not too far maybe that is a cause as well? Here's my latest from my TF-Pro kit:

FC: 5.0
pH: 8.4
TA: 90
CYA: 100

Ultimately I'm struggling most with my numbers, NOT the water. Perhaps I will eventually have water issues though? It's looked perfect since I took over after my first fresh fill from contractor.
CYA is a result of contractor telling me to add 10lbs of conditioner and that was before I found TFP.
 
What is your CH?

High CYA is a significant portion of your TA. Is the CYA only 100 or higher? Have you done a dilute test?

What automation system do you have to control the spa? Please modify your signature to show you have a spillover spa and what type of pool you have, along with volume.
 
Signature fixed

CH is 566 - I'm on well water and didn't know importance of CH when pool got filled either, before finding TFP.
CYA is probably higher than 100. The water level sits a tiny bit below the 100 mark on the dot vial.
Not sure what the dilute test is? Is that the black dot viewer?
 
Sorry, I got some information mixed up. 566 is from the pool store test. I did the CH test with my TF Pro just now again and got 21 drops - (525)

I did the CYA test according to the laminated sheet in the kit. The "extended information" you linked to has a little more information, like "stand outdoors" and make sure you can't see the dot even after staring for a few seconds. I'm going to do that again, I'll bet I'm probably lower than 100...

edit: Nope, I'm still a little higher than 100...
 
Last edited:
Is that a newly plastered pool? Curing plaster can create quite a significant pH-drift.

With TA 90 and CYA 100, your Carbonate Alkalinity (CA) is actually not very high (CYA Alkalinity is about 100/3, the difference between that and TA is CA, which is the pH-driver). I wouldn't expect too much of a pH-drift there, unless you have big waterfalls/spillovers that are running for a long time.

How often are you adding acid, and which pH are you targeting?
 
mgtfp said:
Is that a newly plastered pool? Curing plaster can create quite a significant pH-drift.

With TA 90 and CYA 100, your Carbonate Alkalinity (CA) is actually not very high (CYA Alkalinity is about 100/3, the difference between that and TA is CA, which is the pH-driver). I wouldn't expect too much of a pH-drift there, unless you have big waterfalls/spillovers that are running for a long time.

How often are you adding acid, and which pH are you targeting?
Click to expand...
It was plastered in February. Long story with startup pool guy (he didn't really start up much)
My waterfall/spillway is big. It's about 5' from spa to pool and when I run the pool pump it just barely trickles out of the spillway. I was running the spillway for 30 min. a day but yesterday I turned that schedule off.
I'm adding MA about 2-3 times a week, almost 2 Quarts..
I'm targeting pH of 7.4-7.6
 
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