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Active Member

Posts: 7

Location: USA


Saturday, June 19th 2004, 4:18am

Fertigator Questions

I am installing a sprinkler system at our house to cover our 20,000 sf lawn which will be planted soon. I have installed everything up to the valves including a FertiPro M-1. I am going to finish up the zones and make the final connection to the water source this week but I have a couple questions relating to the Fertigator.

First, I am a little concerned about using the Fertigator in my system right now because I have a double check backflow device and I've heard they are not the most reliable. Any recommendations concerning this? Would it be a good idea to put in a redundant back flow device of another type? If so, what type would you recommend? We have plenty of pressure (~90-95 psi) so I'm not really worried about pressure loss and I am going to add a filter and shut-off valve at the mainline connection so it wouldn't be a big deal to put in another backflow device at the same time. However, any backflow devices are going to be lower than most of the sprinkler heads so I guess that limits my options a little bit. Also, am I correct in that a double check backflow device <b>DOES NOT</b> need to be elevated at least 12" above the highest sprinkler head?

Second, assuming I am going to stick with the Fertigator, I am kicking myself for not putting in an M-1 Double since we have substantial plantings covered by seperate zones which would benefit from a different type of fertilizer than the lawn. It would be pretty tough to add another M-1 with a T coupler right now as space is tight and everything is covered by a weed barrier, bark dust and plantings. Digging it up to add another M-1 would be my last choice of action. With that said, is there a way to integrate another M-1 unit without adding another T coupler to the system? I haven't taken a close look yet but maybe there is a way to splice into the injection tube of the current unit with a second unit? Also, if I am able to do that what would be the best way to control the two units? Should I just add a second eight zone controller or get the AR-3 controller?

Thanks for any help with this. If there is anything anyone wants to add feel free as I am always open to good advice.



Supreme Member

Posts: 456

Location: USA


Tuesday, June 22nd 2004, 7:19pm

If you want to expand, get the add on controller and add another "M" tee. It will save you lots of hassle.

Your backflow will do just fine, if it didn't meeet standards it wouldn't be on the market. You are correct about it not having to be 12" above the ground. That is for a PVB. :)


Supreme Member


Tuesday, June 22nd 2004, 7:39pm

From what I've read (and perhaps you to), double checks are not as reliable as a RPZ. I'm under the impression that in a worst case situation (perhaps freeze damage or junk getting in the line from a broken line) the RPZ is more likely to fail such that backflow with exit the RPZ through the relieve valve, but if a double check fails and the valves get stuck open for any reason, you totally lose your protection. Both devices can be installed below sprinkler heads, but an RPZ must have clearance for the relieve valve to spew water freely without becomeing submerged (hence RPZ's generally can't be installed underground in a meter box like the double check can).

The other thing I heard suggested is that if your system is greater then 80psi, you should install a pressure regulator to reduce the possibility of damaging the system. Keep in mind that dynamics of the system will cause pressure surges in excess of the static water pressure (that's what water hammer is all about). That's why I had to keep my self from laughing when a guy wanted to sell me a filter rated to 80psi to be installed on my mainline that had a static water pressure of 75psi.

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