Wooohooo...a Kush post made it thru...now just to get a few minutes to actually read it?
scanned quickly and get the idea,will reread and actually process the info asap
Following lucas no grow is used at all,but i did in honesty add some when the def was seen.
Your method is pretty similar to mine except that i wasnt doing the half strength nute res as well.
I would top up water,or premix nutes in a 5l bottle and add back(20l tub,devide nute dose by 4 and add to 5l,add back to tub)
Will need to recalibrate by water level,only have it marked in 5l increments and it lacks a bit of accuracy