Let me add here, that Roots love the AIR BATH they
get during a Drain and Replinish in a DWC. This is a very important step.
AFTER the first week, after the seeds have sprouted, the water is still fresh, and you only add 1/4 dose of nutes to the tank at the end of the first week IF you saw two full leaves, besides those very first two round ones.
During the 2nd week, you probably added 1/4 DOSE OF NUTES 2 more times, 3 or 4 days apart.
AFTER 14 days of starting the seeds, you do the first DRAIN AND REPLINISH. Then, again, every 7 to ten days you DRAIN AND REPLINISH. I do it every Saturday afternoon.
BUT, every Wednesday, half way through the week, I drain the tank into a bucket, pH test the bucket and adjust it, and then, after ten minutes of having an empty tank, I add it right back to the tank. That way I did not use extra too many nutes, but I did give the roots an air bath. You will see a RAPID GROWTH SPURT the very next day.
IF you do not have a ppm meter...........
and you do a DRAIN and REPLINISH........Try to think in term of SIXTHS. You got 6 plants, and 6 gallons of water in the tank. AFTER the first 10 days to two weeks, you are going to come home from work one day and find the plants drank half a gallon of water, and need to add half a gallon back. Half a gallon is half a SIXTH, so add half a sixth of a dose of nutes back and half gallon of pH adjusted water.
AFTER two or three weeks, you will check the plants and they will have drank one whole gallon of water in one day. ONE gallon is 1/6 of the tank's water, and if 1/6 of the water is gone, then 1/6 of the nutes are gone, so add back one gallon of pH adjusted water and 1/6 does of nutes.
AFTER 3 or 4 weeks, you will find they drank two gallons in one day. Then add two gallons of water, (1/3 of the tank's water) so also add 1/3 packet of nutes.
If you don't understand this, ask me. It is part of the work or tasks involved in growing.
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