I built a current culture based 9 bin system and just finished the first run out of it a failed crop but here is what happened and the changes made.

First mistake was not insulating the bins and sitting them on a concrete floor, we had a very bad cold snap and the water went from 21 celsius to 13 overnight, the drop was that quick that the Chiller that heats as well as cools couldnt raise it fast enough and the floor would have been sucking heat out of the bins as well, hence a failed crop because the shock stopped them in their tracks at 5wks into flower, the air intakes are down low and the air would have been too cold not helping the situation.

First tip is insulate the bins , roots do not like temp fluctuations that happen quickly and plastic tubs offer no buffer at all, not only can they go into shock and you lose the lot but fluctuations mess with their feeding and metabolism so I come away with thinking this a must do to dial it in.

The next thing was I used 50ml pipe to connect the bins which were 60ltr each with the epicenter in another room connect by 2 x 50ml pipes . What happened was the roots nearly filled the bins and pressed against the pipe outlets and all of a sudden your current flow through the system is reduced big time I dont know if this was a problem because the crop failed anyway but I dont like the way it did it so changed the whole deal.

What I did was build two troughs 2000ml x 600ml wide x 400ml deep , I used treated pine sleepers 50ml thick then lined with carpet underlay and then pool liner, then I connected the troughs using 100ml pipe . This is so much better in every way the plants are perfect and the water system does not fluctuate a degree and the roots have no restriction at all. I also did away with aerators and added a pair external water pumps and just ran a line along inside top of each trough creating lots of splash water movement. Im just pulling down the plastic tub system and putting another sleeper trough unit in its place. While on aerators Ive heard people say your pumping in pathogens, well I dont believe that because the atmosphere air is the same whether you pumping the air or its just passive its the same air, but they do heat the air, I think splashing and moving the water with external pumps is a lot better with no added heat.

My desert climate is extreme with a 20 celsius swing daily so I found having 50ml timber insulation is the way to get the bottom end very stable, the other thing with Flow restriction is worth keeping mind I see problems coming from running the bin connections to small , I wouldnt go under 60ml , I did away with all the bins and made 1 big bin and think its much better

Hope somebody gets something out of it.