er - don't pour nutrients & additives directly into ur dwc tub
premix them in a separate bucket & make sure the ph & ec are what u want
before u add them to the dwc.
I cheat a bit. If I want ec of 2.0 (reads 20 on my meter) I mix up at ec 6.0 (60), then add 1 jug of nutes to 2 jugs of water.
That way i can mix up nutes for total 100L changeout all in 1 go.
Mixing up 100L would take me ages, so I mix up 10L in a bucket & make it 10x stronger than i need, add the required number of jugs on top of fresh water.
Get it?
my tapwater is 7.6ph, so I premix my nutes & stabilise to 4.5 - this gives me the 5.5 - 5.8 that I want (in veg - bit higher in flower)
I have draintaps at the bottom of my dwc's but find it's a lot easier & faster to use a pump attachment in my cordless drill.
This cost £1 & takes less than a minute to empty out a 30L tank - same to fill it
