SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

No, I wouldn't suggest using the Ferti-Flo for an application that big. No, you can't use the Ferti-Pro without the controller unfortunately. Not sure where your backflow device is in relation to your controller, but you can put the Ferti-Pro device right after the backflow on the mainline and run the wires from there. It is a gradual feed system, injecting a little bit of fertilizer every time you water. For that size of a system, depending upon your settings, you can probably expect to refill the fertilizer about once a month or so.

To answer your first question as to the refill size, The FertiPro units actually don't come with a predetermined fill jug. You simply take the 1/4" line from the injector and stick it into the jug in which your fertilizer comes in. It could be a one gallon jug, or it could be a five gallon jug. As for the FertiFlo units, which do come with a holding tank, The FertiFlo 1 comes with a 1 1/2 gallon jug, which covers 7,500 SQ FT - The FertiFlo 2 comes with a 2 gallon jug and covers 10,000 SQ FT - The FertiFlo 4 comes with a 3 1/2 gallon jug and covers 17,500 SQ FT. (These coverage rates are based on typical water schedules.) As far as I know with the fertilizers, It is very important to use only clean, all soluble liquid fertilizers that don't contain abrasives or solids. What I generally suggest to my clients who wish to use phosphate free fertilizers is a product from Abby Science, which is 10-0-3. You can find it at http://www.abbysciencelabs.com/phosphate_free_fertilizer_10_0_3.htm
It is available in different sizes to suit your application. Hope this helps.

If you are using a pump, it is possible to employ a suction-side feeder for fertilizing. No controller needed. The same concept is employed for neutralizing iron in well point systems.