I got my new SWG installed over the weekend and couldn’t be happier to have finally made the switch!
I have noticed something very strange though…
Ever since I put in the SWG, when my pump is running at its low speed (1550 rpms), I have noticed the volume of water flowing over my spa spillover slowly decreasing. It will go from a steady flow to a trickle. I looked at the equipment and was surprised to see it looked like there was a bunch of air in the spa return line’s check valve. If I bump up the pump speed, it clears out the air, and then I can drop it back to 1550rpm and the flow over the spa spillover will be back to normal. Then, a few hours later, it will be back to a trickle and I can see air in the check valve again. The only change was the addition of the SWG, so I decided to turn off the SWG, clear the air from the line and check back a few hours later – sure enough, everything was normal and there was no air in the line. I turned the SWG back on, it started producing hydrogen when making chlorine again, and the spa line appeared to slowly collect air again.
My theory is that there is not enough water pressure at the lower pump speed to clear the hydrogen out of the spa line, so it continues to build up in the pipe. Has anyone ever experienced this before? I am a little concerned with Hydrogen building up as I know it could lead to an explosion.

I have noticed something very strange though…
Ever since I put in the SWG, when my pump is running at its low speed (1550 rpms), I have noticed the volume of water flowing over my spa spillover slowly decreasing. It will go from a steady flow to a trickle. I looked at the equipment and was surprised to see it looked like there was a bunch of air in the spa return line’s check valve. If I bump up the pump speed, it clears out the air, and then I can drop it back to 1550rpm and the flow over the spa spillover will be back to normal. Then, a few hours later, it will be back to a trickle and I can see air in the check valve again. The only change was the addition of the SWG, so I decided to turn off the SWG, clear the air from the line and check back a few hours later – sure enough, everything was normal and there was no air in the line. I turned the SWG back on, it started producing hydrogen when making chlorine again, and the spa line appeared to slowly collect air again.
My theory is that there is not enough water pressure at the lower pump speed to clear the hydrogen out of the spa line, so it continues to build up in the pipe. Has anyone ever experienced this before? I am a little concerned with Hydrogen building up as I know it could lead to an explosion.
