This is what I use. Battery-Operated Liquid Transfer Pump (Black) https://www.amazon.com/dp/B07XKRQLX4/ref=cm_sw_r_awdo_navT_g_BMK4V919WKHJWMHV5VXD
I just dump the old nute water into a bucket, dump the dirty, clean the bucket with tap, fill with RO, mix nutrients, pump back into the plant.
I guess the one thing that would make it faster is if I made one big thing of new nutrients, but I'm running a perpetual grow right now so plants all need different EC. Yesterday I swapped at 1100, 700, and 400. LoL. Takes about thirty minutes, forty if I defoliate. I normally do a full swap ever four days. If I got a week I add extra nutrients on day four.