You're making this too fucking difficult.
Just pour until your nutrient solution comes out the bottom........the amount you start with is irrelevant.
I highly suggest you take the advice in post #9.........
www.cocoforcannabis.com.
Next time start in solo cups.......that way you can feed daily to run off and get faster growth..
Coco is simple.
Feed daily to run off.
Never plain water.
Never let it get dry......even on top.
7 days from sprout........fed daily to run off.
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Good luck.