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?