Thanks for comments all

I was sure i was gonna come back to a dead plant!
Nice work Steely. that root should turn into a massive root ball.
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steely, how is that float valve working? I bought the same one but have not installed it yet. I am definatelt looking forward to not having to fill my res by hand daily.
Thanks Jack, the float-valve works well so far. I had to re-site it once because the net pot was just pressing down on it so it was always on, albeit very slightly.
I suppose the root mass will eventually press down on the valve, too.
I could avoid that by having a wider bucket, so the valve wouldn't be under the net pot.
There is a really small, very slow leak where the intake tube screws into the main valve assembly. It didn't leak at first but only after i resited it so i think once these things are screwed in they are best left ther and not undone then rescrewed, the tolerance must be tiny because it's the tightest screwfit i've come across in plastic.
I'd also like to add a tap to the exit tubing in the topup tank so i don't have to empty it when i need to move it.
Thanks all for reading, i'm really glad the system works but i'm sure there'll be issues or things to add in the future, you all know what it's like!
All the best,
steely