They looked weird an pale with splotchy darker green, the yellow one fell over and so I used a wire to help it up. I had to check back with my 3 in a pot seedlings to confirm that this slow start is nothing to worry about. I know by day 10 or 11 the stems begin to thicken and that is what happened. They went from looking strange to looking sort of normal now.
Replaced the reserviour and no roots have emerged yet which is what I'd expect because there's a lot of substrate in there. Both plants seems to be showing quite different phenotypes though.
This still needs some tweaking and I made some more drain holes where the middle tank overflows to the reservoir, and I might tweak it some more. I do prefer the circular system but this is just a proof of concept.
I'll be expecting some proper action by next week.