Ph Drops when pump is on low speed, why? (Hayward pro-logic, 13,000gal SWpool w/chlorine generator)

mguzzy

Well-known member
Jul 8, 2015
446
OV, CA
Mguzzy,

The OP's pH is not actually dropping into the 4's.. the system is just reporting it is in the 4's.. A typical problem with automated dosing systems..

Jim R.
Exactly.. I suppose I should ask if the number's he is reporting is from an independent test kit or what the system is telling him.
 

~STOLEN~

Member
Jul 11, 2019
19
Indianapolis, IN
Exactly.. I suppose I should ask if the number's he is reporting is from an independent test kit or what the system is telling him.

the independent test was exactly what the sensor read this morning this morning which was a pH of 4.9
(i wish i had opted for the wireless setup, so i could check this as we are chatting)

Someone asked a question that directly relates to WHAT im trying to solve.

i and NOT going through acid like crazy, because the dispenser times out when pump is on low speed, Which lets me know that it isn't because of TOO MUCH acid, its gotta be something else.
the ph is dropping 2.5 points over a 10hr span and the ONLY thing that i do to bring it back up is run the pump on high speed

I'm hoping that the other tests from the kit mentioned earlier can shed light on a couple things that may be out of whack
 

JamesW

TFP Expert
Mar 2, 2011
15,509
What are you doing to independently test the pH?

The actual pH is not going to go back up just by running the pump at high speed.
 

~STOLEN~

Member
Jul 11, 2019
19
Indianapolis, IN
HEY guys, another update here. I took a snapshot of the setup when i got home, and also remembered someone asked how old this system is. It was installed in MARCH of this year.
I did notice that that chlorine generator is for up to 40,000gal, and my pool is only 13,000--is this an issue that its too big?

When i came home, the pH was at 6.9
The acid hasn't been used all day because it had timed out again on high speed due to still having low pH.
Then i went around and did another manual pH test and mine came up at 7.0-------.1 off the manual which is acceptable.

There is still in my opinion NO rhyme or reason that just high speed filtration will make the pH go up on its own. But it does on my system.

Are there any other things that you would suggest or need to know about this system to pinpoint the drop in pH my pool has on low speed filtration? I will have that other water test on order in the next day or so.

Thanks again for all the help and input towards figuring this out guys!!!
If any of you live close, swing by for some ribeyes & beer on me!! supposed to be in the 100s this weekend here :cheers:
 

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JamesW

TFP Expert
Mar 2, 2011
15,509
The actual pH is not rising due to the pump running on high. That just can't happen unless you have something pumping sodium hydroxide or another base into the water.

The influent to the sense and dispense is supposed to be after the filter. Where it is installed after the pump can allow debris to get in the equipment and might be causing problems.

What is the model number of the Sense and Dispense?

What is the software revision for the ProLogic?

What is the model number for the acid feeder?
 

~STOLEN~

Member
Jul 11, 2019
19
Indianapolis, IN
The acid is dispensing after the pump and filter

Here are pics of everything else currently
 

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JamesW

TFP Expert
Mar 2, 2011
15,509
You have two black tubes that go into the sensor bay.

The one on the left at the sensor bay is the influent (water going in). The influent should connect to the plumbing after the filter. The influent is currently connected to the pump suction, which is incorrect.

The tube going into the right valve at the sensor bay is the effluent (water going out (egress)). That tube should be connected to the pump suction.

You need to have someone who knows what they're doing go over the installation and verify that everything is installed and configured correctly.

Honestly, I would get rid of the sense and dispense. In my opinion, it's a huge waste of time and money.
 
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Fast7

Well-known member
Aug 8, 2018
180
Plainfield, IL
The ph timeout settings are only 60/90/120min
These settings are to select a time feeder automatically shut off due to running continuously for 60/90/120 minutes.
These are not inactivity settings.
If you are getting "check system" alarm I would check to make sure your acid feeder pump is not getting triggered and running continuously for set amount of time.
With that being said, however it wouldn't be possible to bring pH back up in such a short amount of time by running pump on high speed.
There might be installation error as other mentioned.
 

~STOLEN~

Member
Jul 11, 2019
19
Indianapolis, IN
Is it possible that the acid mix is too heavy?
I put 1 gallon of acid to 3 gallons of water in the feeder
Again low ph this morning
Per the settings the dispenser hasn't came on because ph hasn't been over 7.9 and the tank is still full from over a week ago when I filled it up it's not inning non stop
The level in the tank suggests that it hasn't been much at all

I think I'll just go back to the speed settings from the Hayward default and see if it comes back to normal again.
There is no chance I'll ditch this after spending all that money on it just 4 months ago. I'd loose my Rear on it

I'll run the old settings and report back Friday afternoon when that test kit comes in


Again thanks a lot for the direction and help fellas!!!
 

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Apr 5, 2019
19
Davis, CA
Is it at all possible that the low speed does not create enough flow for proper dissolving and most acidic water is at the top layer(s) where the sample is taken from?
 

JamesW

TFP Expert
Mar 2, 2011
15,509
It's installed incorrectly. You need to fix that first. It's not going to work correctly when it's not installed correctly.

Call the people who sold it to you and tell them to get it installed correctly and working properly or to remove it and give you your money back.