You don't need a tee. Just use the flojet with a different jug with descaling solution only?

FWIW a tee after the flojet would not make much sense? Unless you did not need it to provide positive pressure to the machine in the first place..seems some people are running the Vetrano without flojet.

Some more info here:

Water, Scaling and Descaling with HX machines?

I thought that one issue with the rotary pump machines like the Vetrano and the Vivaldi II is that the pumps don't suck from a reservoir (hence the need for the flojet systems). I have a Vivaldi and you can pour a descaling solution into the steam boiler from the top if you remove one of the fittings. Since the steam boiler is the only one that ever boils it should be the main place where any scale may develop.

Clearly my comments are not completely appropriate to a Vetrano, or other HX single boiler machine.
Mark

@ eastpresso I didn't think that a T would be of much use after the flojet either, but I wasn't sure if you could get away with just using the machine pump for a short time. Thanks for the response! Let's see if I can do this without hurting myself.