IntellipH siphoned 3ga of acid overnight

[Steve_K]

I self-installed an IntellipH last week and it has been operating well until now. During the night, while the pool pumps were off, the acid tank was completely drained, so 3 gallons of acid went into my pool. I can only estimate the pool pH is around 6.0, since the Taylor test kit only measures down to 7.0. I added 24lbs of Borax (I cleaned the shelf at Walmart) to bring the pH up to 6.8 and I'm aerating the water to bring it up further.

So, what caused the IntellipH to drain all the acid in the tank??? The pool pumps were off all night, meaning the IntellipH controller and acid pump were without power. So the acid must have been siphoned out of the tank through the acid injection line. To create a siphon, there must have been negative pressure in the pool return light were the acid is injected (just before the IntelliChlor). But, what would cause this negative pressure? The roof mounted solar collectors where operating yesterday to heat the pool, so could water draining out of the collectors during the night create a suction? Apparently the IntellipH pump can't hold a vacuum on the line, as the acid passed through the pump when it was siphoned out of the tank.

Any suggestions? Is there a device that can prevent negative pressure on the pool return line or prevent the solar collectors from draining when the pool pump is off?

Steve

 

[makinc]

Can you post a pic of your installation?

 

[Shirker]

Does your tank sit above the water level and possibly have a leaky valve? Sounds exactly like you say, it just siphoned it all out.

 

[Steve_K]

I may have found the culprit. I've couldn't understand how the acid could travel through the IntellipH acid pump when the pump was turned off. Looking at the pump, I noticed the clear plastic cover the protects the pinch rollers was not locked in place, and had shifted up away from the rollers. The plastic cover performs an important function... it presses the pump's surgical tubing firmly against the pinch rollers. When the cover is loose, the tubing is no longer pinched shut and acid has a free path to travel even when the pump is off.



I'm still not sure what caused the siphoning to start, I suspect water was draining from the solar collectors on the roof. I'll talk to the installer tomorrow to better understand how they drain. Regardless, they IntellipH should not siphon anymore so long as the pump cover is locked in place.

Once the pH has returned to normal, I'll refill the acid tank with only an gallon of acid and keep a close eye on it.

 

[makinc]

I think you are correct. I also notice you have the redesigned pump head. This pump head started with units manufactured in August 2014 per the revised manual. Much better design.

 

[makinc]

Did the cover become unlocked during operation or did somebody turn the tab?

 

[Steve_K]

Someone turned the tab, as it takes some effort to unlock it. I had a service guy look at the unit a few days earlier and I think he unlocked the cover during his inspection and forgot to lock it. I've had numerous problems with the unit since I installed it a week ago.

Initially, it would not inject any acid. I found the motor head was turning in the reverse direction! I believe it is a DC motor and apparently the power to the motor is reversed. To resolve this, I swapped the acid inlet and outlet hoses.

After fixing that, it still would not inject acid. I found the check valve (located inside the injector nozzle) was stuck shut. The valve is just a soft piece of rubber similar to the nipple on a baby bottle, but much smaller. I just poked it a bit and and it started working.

I'm still working with Pentair to resolve a bigger problem... at the 100% setting, the IntellipH still does not add enough acid per hour to maintain the proper pH in my pool. My pool has an infinity edge and a waterfall feature, plus the fill water has a high pH. I need 1.5 ga/wk of 33% acid to maintain a pH of 7.6. But, the IntellipH is only putting out 2 oz/hr at the 100% setting. That works out to 112 oz/week which is less than one gallon. This all assumes I run the pool pump for 8 hours a day. Sure, I could run the pump for 14 hours a day to increase the total acid injected, but that also increase the aeration from the water features which increase the pH. So, it's catch 22.

The only solution is for Pentair to change the IntellipH software to allow more acid per hour. I have no idea why the max acid is set to 2 oz/hr. Seems totally arbitrary to me.