Doser hook up Question? Re: check valves
 

Is it necessary to install check valves in the delivery lines if your doser is delivering to above itself? I don't have a sump so the unit is to be under the DT & pumping up. So i wonder if back flow could be an issue? It's a Ghl 4 pump. thanks.

It probably wont be an issue unless the hose comes off the plastic connector from the peri tubing. In which case you would get a back siphon from DT. It would be a very rare event for that to happen. Especially if you made sure the hoses were all the way onto both steps of the plastic fitting.

The hose's won't actually be in the water in the DT, they'll be above it. I wasn't worried about a back siphon. I wonder if the additives in the lines may flow back down, causing air in the lines that could lead to lag time during a on/off cycle causing a weaker than anticipated delivery of supplement's. Or if the pumps keep enough pressure in the lines to keep them continuously primed? If I was to install the checks they would be just short of the point of delivery, again only because the Dt is approx 3' higher than the unit.

I wouldn't bother. The rollers will prevent anything from flowing any direction other than forward.

And since it comes out above the water line, you're 100% safe from any other issues.

No check valves and my SA3 is working perfectly.

Sweet, less work is better. That's why I bought the SA in the 1st place. No more over-thinking, just calibrating. Thanks guys.

I pump 6 or 7 feet up. My pumps put out 47mL/min since you didn't ask =)

The GHL doser motors all come with 3 rollers which will actually help to prevent back flow, so ya, no worries there.

However, not all dosers are created equal. There are a lot dosers with just two rollers and with only two rollers there is definitely the potential of back flow.