Farmers all around the country have been using fertigators for years. Are you wondering about the physics of sucking fertilizer into the system or are you wondering how well it works?

More about how well it works vs. standard fertilizing.

My gut feeling is that it gets the fertilizer out there quickly but there could be side effects. Time released fertilizer might not work. Poor coverage could result. Fertilizer could wash down the street. Corrosion of any metal parts in the system or sprinkler heads. Sprinkler valves could stick open or closed and nozzles could stop-up. Potential water contamination due to back-flow if a failure occurs. I would opt for conventional methods of fertilizing rather than invest in an inline system. Too many things could go wrong.

i understand it's a 2 yo thread, but just in case. i do have one of those installed into my irrigation.
i did installation myself. was few bucks worth of parts from home depot.
it works by running off water flow in the system. judging from the noise it makes, there's a turbine in it that is propelled by water flow and that propels some sort of a pump inside the housing that creates suction, sucking in certain amounts of liquid fertilizer from a can/bottle/canister.
i am probably not a good source of opinion on results, as i live on a very, very poor soil acre. fertifator squirts in minute amounts of fertilizer, so it does not give tremendous results when sprayed over 25000 sq feet of grass. also, it should be proportional to time irrigation is on, and i do not exceed 17 minutes per station.
also, i combine inline fertigation with broadcast spraying from my 14 gal sprayer, but i started doing this only 2 mths ago.
so far, grass is still there. comparing to the last year, when i had 45% of it dead after drought.
i have no weeds, as i add weed killer to the liquid.
truly, i will know by september, as heat wave finally came to pacific nw, but this time i'll go for broke and keep watering.
part of the issue you will have with fertigator is you are getting hassled with finding liquid fertilizer. stores do not have it. best i could find was miracle grow 4 bottle packs from walmart, at $10.
liquid fertilizer canisters that will work with mine run about $25 plus shipping and should last about a month. that's really something to consider before you fork for one.
what i did, i said froget that expense, and figured how to use regular 2L coke bottle for fertilizer. i simply mix mine and pour into the bottle. 2L lasts about 10 days on 5 days a week irrigation, so i simply watch for the level to drop beyond certain point and refill.
i use - blasphemy - miracle grow mixed in water. i feel confident, i could also use fish fertilizer solution in water. heck, i could use black water from my septic. whatever is soluble in water without major solid particles left will work.
now i need to find inline fertilizer that will connect into hose garden, for back yard, as i do not have irrigation there.