The mfr of the nutes I use (Canna) recommends bi-weekly dumps and tank cleanouts with plain water top-up if needed and pH correction on top-up.

I've got 550L (145gal) of tanks to dump every 2 weeks. I use a flood system, so each tray has its own pump. I used a garden irrigation tee fitting and 2 irrigation valves on each tank to make dumping easier.

Just close valve #1, open valve #2 & hit the pumps- and as soon as I've had a coffee, tanks are drained and ready for cleaning & new sauce.