What are you guys using for fertilizer flow/rate monitoring on your corn planters? Costs?

I farm in Michigan with my father and brother. We run a JD 1775NT 24row 20" putting down 2x2 and in furrow both liquid. We've had red balls on past planters. Red balls worked decent in past. They are relative though and your craning your neck unless you point a camera at them. Set this planter up with microtrak electronic monitoring (basically flow no flow). complaints are unrealible, rows may be partial blocked, rate changes require sensor modification. Looking at changing to something that monitors actual applied rate. Would like something electronic that is ISO and can run in the JD 2630. Please let me know what you guys are using and relative costs. Thanks!