Would it be harmful in getting my pool to a pH of 7.3 or 7.4 range when I treat it with acid. When pH gets to 7.8 I drop it to pH 7.5

For kicks I sometimes check it & sometimes it’s a tad below 7.5, man it sure needs less chlorine the lower the pH is. It has gotten to the point where I don’t even bother checking pH until the chlorine demand goes up more than usual- then I know my pH is creeping up to where I need to be checking it.

FWIW, I had a calcium scaling issue (winter pH got too high for too long) that I tried to correct with various acid treatments that were unsuccessful, I haven’t re-plastered & won’t until I have to.

Current tests & been stable all summer- pool has behaved spledidly all summer
Borates 25
TA 50 & has been all summer & doing great
CC 0
CYA 45
CH 300

Thank you

Taking the PH down as low as 7.2 for fairly short periods is always totally fine. You don't always want to do that on purpose, for example lower PH tends to cause more PH drift, but if it happens now and then it isn't a problem.

TA around 50 is fairly low, particularly without any borates in the water. I don't recommend TA below 60 without borates. 50 is not really a problem, but you don't want it going below that, so keep an eye on it.

No.
I try to keep mine around 7.4, since I read somewhere that that's the pH of human tears.

Plus I have a lot of CH, so I need to watch the CSI.

Richard,

How does it feel? I ask because 1) I don't bother to swim so I ask my kids, and 2) when I had the pH at 7.4 the kids said their eyes stung a little. I've brought it up to 7.5, maybe 7.6 and the kids say it's better.

I also have cold water. So, I think that might be a factor as well. Trying to find the right pH for eyes has been difficult for me this season. It's not 7.4 for sure. Pool was holding at 7.7 earlier this season and the eye issue was hit and miss (kid report). Then I stuck two 3" pucks in it, pH went down to 7.2 and I had to aerate. Takes me two full days to aerate a tenth up with my hokey aeration techniques.

I've been wanting to ask how everyone's eyes feel at different pH levels. The kids seem very sensitive to the normal range, needing something specific that I am not sure I have figured out quite yet. Thoughts?

(prolly should be a new topic, but it seems to fall into this one as well. How does the OP's eyes feel?)

See this post. According to the studies, a range of pH from 7 to 9 is not irritating to the eyes, but the eyes are much more sensitive to the salt level where higher is better (well, ocean salt levels are too much, but normal pool levels are all below the 9000 ppm level in tears). Now chloramines, especially nitrogen trichloride, is very irritating and more of it is produced at lower pH, but with CYA in the water their level should be negligible. So I'm not sure what accounts for your kids reporting that 7.4 is irritating while higher pH is not. I've had the pH from 7.0 to 8.0 at various times in the pool (the former during TA lowering) and I never noticed any difference for my eyes.

I hardly ever see CC. I test frequently.

They report honestly. They know I need accurate reports. The community center pool down the street always leaves them with bad eyes. They tell me when our pool is off. They know it can be perfect.

" mom, the ph is off..."

Tfpkids for certain, lol.

It feels like nothing. When I get out of the pool, I may as well have just gotten out of the shower. No smell, no red eyes, no itchy skin, no dry hair.

If 7.0 pH is classified as neutral, wouldn't 7.0 to 7.2 pH be best for a marcite pool? In other words, in that range the water in neither acidic (that would cause pitting) nor alkaline (which would encourage scaling).

Whether or not the plaster will scale or dissolve depends on the calcite saturation index (CSI), which depends on multiple factors. You can use the pool calculator to calculate the index.

http://www.thepoolcalculator.com/

I'm not a big swimmer, so no help. Nobody complains. It is not at 7.3 or 7.4 for too long because it always creeps up.

Right on re keeping an eye on it Jason, you helped me last season when I 1st discovered a TA of 50 is good for my pool. My Borates are 25 as I say. I always figured I'd not replenish my borates when they are gone,but, based on well my pool has behaved this season, I may re-think that if I have issues w/out borates.

My TA of 50 has been 50 since opening & I have not needed to add anything to keep it there.

Is everyone estimating pH of 7.4 or 7.3? The pH test that came with my TF-100 has color matches for 6.8, 7.2, 7.5, 7.8 and 8.2. If the color appears to fall between 7.2 and 7.5, do you say that the pH is 7.3 or 7.4 depending on whether it's closer to the 7.2 or 7.5?

I can easily distringuish between 7.2 and 7.5 (and I can sort of guess when the shade is between the two) but when it gets above 7.5 the shades of red/pink pretty much look the same to me.

Yes. With a little practice, you'll be ables to discern if you're closer to 7.5 than 7.3, which makes it 7.4, and so on. I find it helps to hold the test block at arms length with a white background (I use a cheap vinyl stacking chair since it's right there) and sort of squint so it gets a little blurry.

I've had a ton of practice (everyday for 9 months!) and I think it's still a guess whether I'm closer to 7.2 than 7.5. I really have a hard time with the red/purple of 7.8 and 8.2. The red/purple thing is too close. I don't think I've ever had a purple result.

in all reality, is there any significant difference between 7.3 and 7.4?

Since the scale is logarithmic, the difference is actually larger than it appears. A pH of 7.3 is about 1.26 times as acidic as a pH of 7.4.