pH and alkalinity question

Hchang

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Sep 1, 2020
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Austin, TX
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Not worth bothering to interpolate between the graduation marks. The scale is logarithmic, not straight forward to read in-between the lines. If the dot disappears between 40 and 50, just round up to 50 and call it a day.

One more thing to consider, is to make sure to compare pH-readings at the same points within the chlorination cycle. When we say that bleach is pH-neutral, that means that the chlorination cycle is pH-neutral. When you add bleach, pH will rise. Once FC is back to where it was before adding bleach, that pH-rise will be compensated, as the "use" of chlorine (by killing germs, oxidizing stuff and by UV-decay) is an acidic process. Without the pH-drift by CO2-outgassing, pH would be back where it started.

That means that if you allow large FC-swings by letting FC come down to below min (with CYA 50, your min FC is 4, but you seem to let it come down to 1.5) and then adding a big splash of bleach, you will also have a considerable pH-swing withing your chlorination cycle (not a drift, but a cycle). If you start at pH 7.6 and add 81oz of 12.5% bleach (from your PoolMath log), pH will be nearly up at 8 (assuming TA 60). Starting at pH 7.9, these 81oz would get you up to 8.3. That is not due to the CO2-outgassing drift. But you might misinterpret this as part of the drift when comparing pH-readings taken at different points within the chlorination cycle.

Try not to let your FC go below min (which you should anyway as you are at risk of an algae bloom by allowing FC drop below min). Add smaller quantities of bleach more often, and always compare pH-readings from the same point in the chlorination cycle when estimating the pH-drift.

The effect on pH directly after adding chlorine gets sometimes forgotten, and that the statement of bleach being pH-neutral has to be seen over the complete chlorination cycle. Here a quick refresher from Chem Geek:
Thank you for this. Good to know about the CYA reading.
I think I follow you about the chlorination cycle. Most of my pH readings have been when the chlorine is also reading lower, prior to adding bleach. So I thought I was getting readings at the end of the cycle???

So you are saying that the lowest my chlorine should read is 4 and I should add more when it hits that? Should I shoot for a lot higher? I was thinking 4 was my goal and that I should try and maintain that on average but that as the chlorine is used it would drop below that and that’s when I should add more. I’ve been adding every couple of days. It seems to maintain at 4 or more for a couple of days and then overnight it seems to drop to 1.5-2. And at that point I add chlorine (and acid because the pH is still high).
again thanks for your reply. Still learning!
 

mgtfp

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Mar 5, 2020
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Thank you for this. Good to know about the CYA reading.
I think I follow you about the chlorination cycle. Most of my pH readings have been when the chlorine is also reading lower, prior to adding bleach. So I thought I was getting readings at the end of the cycle???

So you are saying that the lowest my chlorine should read is 4 and I should add more when it hits that? Should I shoot for a lot higher? I was thinking 4 was my goal and that I should try and maintain that on average but that as the chlorine is used it would drop below that and that’s when I should add more. I’ve been adding every couple of days. It seems to maintain at 4 or more for a couple of days and then overnight it seems to drop to 1.5-2. And at that point I add chlorine (and acid because the pH is still high).
again thanks for your reply. Still learning!

Have a look at the FC/CYA Chart. You should aim to be in the target range at all times. The min really needs to be seen as a level you never want to be under. You always want some buffer towards this to have room for an increased chlorine demand due to an unforeseen pool party. Or you miss a chlorine addition due to work commitments or other reasons. You shouldn't "plan" to let FC go down to min.

With a Salt Water Generator (SWG), the target and min values are a bit lower. Because of the permanent chlorine generation you are at less risk to drop too low, and because of the higher chlorine concentration within the SWG-cell there is a permanent super chlorination happening to the water flowing through the cell. That's something to consider for the future. There is a some upfront investment in getting and installing the hardware, but after that you don't have to buy much chlorine anymore (always good to have some handy for quick adjustments, but you won't need much), and pool maintenance nearly gets boring...
 

mgtfp

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Mar 5, 2020
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Melbourne, Australia
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I think I follow you about the chlorination cycle. Most of my pH readings have been when the chlorine is also reading lower, prior to adding bleach. So I thought I was getting readings at the end of the cycle???

What I found really helpful was to measure pH a couple of times a day, especially before and after adding chlorine (giving it enough time to mix in), over a period of a couple of days. That gave me a much better feeling for fluctuations within the cycle and the general upwards drift.
 

Hchang

Member
Sep 1, 2020
18
Austin, TX
Pool Size
17500
Surface
Plaster
Chlorine
Liquid Chlorine
What I found really helpful was to measure pH a couple of times a day, especially before and after adding chlorine (giving it enough time to mix in), over a period of a couple of days. That gave me a much better feeling for fluctuations within the cycle and the general upwards drift.
Great idea. I will do that starting tomorrow!
 
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Hchang

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Sep 1, 2020
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Austin, TX
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Page 51 of your Intellicenter User Guide.
Here is a picture of my equipment. Do you think I have the ability to set my Wasytouch up in a way that the waterfall is turned off but pool still circulates water and not have to be in spa mode?
 

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mknauss

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Yes.

Turn off the red handle ball valve to the far left. The spillover should stop when in Pool Mode.

Set up a Spillway circuit. Schedule that to run for 30 minutes or so twice a day. You may want to adjust the pump speed for that circuit to make the spillover size appropriate.
 

Hchang

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Sep 1, 2020
18
Austin, TX
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Yes.

Turn off the red handle ball valve to the far left. The spillover should stop when in Pool Mode.

Set up a Spillway circuit. Schedule that to run for 30 minutes or so twice a day. You may want to adjust the pump speed for that circuit to make the spillover size appropriate.
This one? I circled it in the picture.
The three valves to the right of that one are labeled : pool returns, cleaner return and bubbler.
Yes.

Turn off the red handle ball valve to the far left. The spillover should stop when in Pool Mode.

Set up a Spillway circuit. Schedule that to run for 30 minutes or so twice a day. You may want to adjust the pump speed for that circuit to make the spillover size appropriate.
I can’t thank you enough! I figured it out and was able to create a circuit for the spillway! Basically created a circuit that activates the B actuator and turns off to pool and on to spa. My only issue is that it seems to reflect whatever pump speed I have on at the time. So when the pool is in high mode (3100 rpm) and I turn the waterfall on, it comes on at full speed. I tried to assign a pump circuit at a lower speed to the spillway circuit but that didn’t work. I will keep working on that!
 

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Hchang

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Sep 1, 2020
18
Austin, TX
Pool Size
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Chlorine
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Anyone who returns to this thread. I can’t thank you enough for all your advice. I was able to sort out a better way to run my pumps and waterfall. I checked my chemistry this morning and Chlorine was low again at 1.5 and pH was 7.9 again. But I dosed this morning and got the chlorine up to 7.5 and pH to 7.4. I’ll be working on keeping those in a better range. Again thank you all so much!
 

mknauss

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To change the pump speed, go to MENU ▼ SETTINGS ▼ INTELLIFLO PUMP # 1▼SPEEDS

Select the Spillway Circuit. Change the rpm to the speed you want for when the Spillway comes on.
 

Hchang

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18
Austin, TX
Pool Size
17500
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Liquid Chlorine
I
To change the pump speed, go to MENU ▼ SETTINGS ▼ INTELLIFLO PUMP # 1▼SPEEDS

Select the Spillway Circuit. Change the rpm to the speed you want for when the Spillway comes on.
I must be doing something wrong. I was able to follow your above directions. And was able to select the spillway circuit and dial in a a speed. My pool is on high right now and when I turn on the waterfall the pump still remains at 3100. It’s like two pump speeds are running at the same time. I could manually turn the 3100 off of course. But I’d like to schedule the waterfall or even when I press the waterfall feature button for it to cancel the previous pump setting. Hope that makes sense. See attached image and thank you again.
 

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mknauss

Mod Squad
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May 3, 2014
37,235
Laughlin, NV
Pool Size
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SWG Type
Pentair Intellichlor IC-40
If you have two (or more) circuits scheduled at the same time, the one with the highest rpm will rule.
 

mknauss

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May 3, 2014
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Are you chlorinating your pool with trichlor using the feeder as shown in your pictures?

You also should not run the pump at full speed, I would limit max speed to 3000 rpm.
 

Hchang

Member
Sep 1, 2020
18
Austin, TX
Pool Size
17500
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Chlorine
Liquid Chlorine
Are you chlorinating your pool with trichlor using the feeder as shown in your pictures?

You also should not run the pump at full speed, I would limit max speed to 3000 rpm.
Oh no not using the chlorinator at all. Only liquid chlorine. Thankful I learned that lesson early here!


and that’s what i thought about the schedule. I can turn down the high mode, someone mentioned my speeds (set by the pool company) were too high. I only have the pool/spa system on high mode foe a few hours a day, the rest of the time it’s in low. I need to lower the over all speeds of both. But I guess because I have the VS pump to run at some speed 24/7, the waterfall will run at whatever speed the pump is scheduled for if it exceeds the waterfall circuit speed. I can work with that! Thank you!
 

mknauss

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Yes, you need to rework your speeds.
I would suggest a Pool mode level of 1200 rpm or so. Be sure that skims your pool surface.
Then you can make the Spillway speed anything over 1200 rpm.
Spa can be whatever you need to get the spa action you like, preferably with the speed at 3000 rpm or less.
Your Heater active speed does not need to be so high either. Your heater should work at an rpm of 2000 or so.

You can set a max speed on the pump. Also change the priming speed if you like.
 

Rich807

Bronze Supporter
Jun 21, 2020
80
Las Vegas, NV
Just went thru some of this last week & the mods helped me. Lowest I can run my vsp is around 1450rpms to get at least a trickle of water over the weir door in the skimmer. Have to have at least that much rpm going & as I’m sure you’ve heard from the pros here... ‘every pool is different.’ Don’t get hung up on an a generic #. What gets done for your pool is what gets it done.

My pump running 24/7 at 1450rpm is still dirt cheap electrical charge wise (like $20 a month). Thanks to the mods for pointing that out!
 
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Bvacchiano

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Apr 6, 2018
324
Sugar Land, Texas
I put Zero faith in these digital PH meters (it also did salt,,temp, and useless ORP). I bought one before I got on TFP. I calibrated it then put it in a standard solution and it read perfect. When I put it in the pool it never read right. I just use the Taylor kit now. Waste of money in my opinion....unless you are colorblind then can see the need for a digital meter.
 
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PoolGate

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I constantly battle high pH. Always up around 8. I can add a gallon of Muriatic and within a few days I am up around 8 again. My T/A is around 90+ right now so I am in the process of "pre-loading" acid in an attempt to get the pool to stabilize at a lower pH. This morning my pH measured right around 8, I added a gallon of Muriatic acid, that dropped pH to around a 7. I have both waterfalls running full blast. Hopefully with another gallon or maybe 2 (of Muriatic) after this one I can get my T/A down to around 60.
 
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Prickly

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Jul 8, 2020
122
Kelowna
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Hayward Aqua Rite (T-9)
I got fed up with having to add MA every couple days due to constant pH rise and got the Poolsmith CO2 system. It's a simple system that doesn't need an ORP probe and it's been maintaining my pH perfectly. Another member started a thread documenting the setup and use of it
 
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Hchang

Member
Sep 1, 2020
18
Austin, TX
Pool Size
17500
Surface
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Chlorine
Liquid Chlorine
I got fed up with having to add MA every couple days due to constant pH rise and got the Poolsmith CO2 system. It's a simple system that doesn't need an ORP probe and it's been maintaining my pH perfectly. Another member started a thread documenting the setup and use of it
Thank you. I will look for that thread!