Doser hook up Question? Re: check valves

[spawn]

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.

[TimT]

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.

[spawn]

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.

[cwatkins]

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.

[lastlight]

No check valves and my SA3 is working perfectly.

[spawn]

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

[lastlight]

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

[kien]

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.