DIYbanter - View Single Post - Acid injector for pool

Bob F

wrote:
I have a new plaster pool and they use lots of acid for the first year
or so. I've plumbed a line from the inlet side of my pump to a tank
with 3 parts water, 1 part acid. I'm using irrigation drippers in
line to regulate the flow and have it just right so it keeps the pool
pH level correct. I know of other people who have done this and it
works long term.

My problem is that when the pump shuts off, a small amount of the acid
still siphons into the pool plumbing. Maybe because the tank is
slightly higher than the pool level? Its about a quart over night.

I was thinking maybe a small spring loaded check valve would help,
where just the spring pressure would be enough to stop the siphon
flow, but when the pump is on and creates a vacuum, it would be enough
to move the spring. Any ideas?

You could use a venturi, like the ones used on ozone systems for spas, on the
output side of the pump system, so that it will suck in the acid when the pump
is running. This, and a check valve between the pump and the venturi will keep
the acid out of the pump and filter. This would be similar to the installation
of a chlorinator on a spa.

They make check valves for use in ozonator lines to keep water out of the
ozonator. You can also buy tiny check valves at aquarium stores. Finding one
that is acid resistant may be a problem.

A spring check valve with a metal spring will have problems with the acid. One
aquarium check valve I've used has a rubber internal valve that might close
tight enough. It's clear plastic, so you could visually inspect it for
deterioration.