some of this is fact, and some of this is my opinion..
one of those pumps per bucket will do ok, more air = more bud, but dropping to 7L/m is certainly not going to harm the plant
if I were you I would buy the water and mix it with your tap water until you see an EC of 0.2, that won't harm your plant at all and it will save you buying so much water.
I would do that for the first grow and then switch to tap water for the second, if you see any problems just top up your tank with the store bought water.
test your nutrient solution every day. if the strength rises its too strong. if the strength falls, it's too weak.
the idea is to get the water and dissolved solids the same ratio as the plant is currently using. that's the goldgrower method. it works for me, I never get any nutrient issues be it under or over fertilised
I would cut a 1cm cube of rockwool and use that to germinate each seed. you can put it in the system right away then and it gets more air and grows faster.
ScrOG is a great way to maximize the usage of the light. with a 600w lamp there's probably not that much need to go to the trouble as it has so much penetration of good light. for smaller grows it makes a big difference though
I wouldn't bother with led, they are total rubbish compared to hps watt for watt or cost for cost. if you want to up the lighting I suggest buying a dimmable 600 watt hps now, and when you want to add more light buy another 600w dimmable hps. you can then run both on 400watts giving you 800watts and you will have a far far better result compared to adding 200w of led. you can then have both running on 600 if your ventilation can handle it.
if your reason of adding dry ice is to add co2, in my experience adding co2 only makes a difference if you have everything else spot on and even then your far better off using co2 from a bottle or fire extinguisher. using dry ice isn't worth bothering with. when using co2 you need to have cool tubes so you can close all other ventilation while adding it. otherwise it will get sucked out straight away. your better off spending your money on a bigger exhaust fan and better circulatory fans. this will give you plenty of co2
Edited by GoldGrower, 05 August 2013 - 01:52 AM.