Some parts. Feeling festive…gonna write you a list 
2 x Klamtare 58 x 45 x 30cm storage boxes (totes to our US counterparts)
4 x 10l buckets with lids
1 x 1500lph pump
1 x 1 way valve (for hosepipe)
1 x 12v solenoid valve 1/2" thread
2 x hosepipe tap connections (with 1/2" connectors)
1 x float switch
4 x IWS oxypot net pots (good size) currently only have 2 but 2 more on the way.
1 x 12v NC solenoid valve.
1 x toilet brush holder 
3 x PG9 cable glands (5 if using a separate housing for sonoff basic)
1 x sonoff basic
1 x sonoff TH16
1 x inline butterfly valve
1 x 12v driver
1 x air pump
1 x air pump manifold (2 way)
15 x m25x15mm sealing glands
Hosepipe and air pipe
Right now some details
Usually flood and drain systems work on 2 float switches and 2 pumps. But seeing as the reservoirs are below the pots. This allows the possibility of a gravity return. Minimising pump heat and the necessity for a 2nd float switch. With really limited space I needed to come up with a “control bucket” that would fit the space without hindering the amount of pots I could fit. So I used a toilet brush holder to make it.
These are the Klamtare boxes. Picked because they’re heavy duty. Lightproof and more to the point when joined together make up a pretty much perfect footprint aswell as working as under pot reservoirs.
I’ve tried to keep the necessary tooling to a minimum for this so you know literally anyone could do it without a massive spend. I used my battery drill. A step bit and a Stanley knife to do the entire build.
In each tote (you’ll see they taper in a bit where they meet…perfect) you drill right at the bottom to fit an m25x15mm sealing gland to each which will be joined together to make “the res” using a bit of hosepipe.
Try to make sure these are as level and parallel as possible whilst Being as low as possible too.
On the back of each tote as high as possible you need 1 PG9 connector for air pump tube and on one tote of your choice a second PG9 connector for the feed pump AC wire.
This was my effort. The m25x15mm gland you see is for the feed pump out.
From the pump you see a one way valve. This ensures when the float switch hits and the pump stops. The water doesn’t try to return back to the res via the feed pipe.
This is the 12v solenoid valve and 2 x tap/hosepipe connectors. I chose 12v which is more work and an extra driver because the electrics sit below water level (just a personal choice safety feature)
Hosepipe slots over either side nicely now 
There’s an arrow on the valve to show the direction of flow. It points down for the record.
There’s the basic idea. If you pay attention to the glands in particular here. You’ll see the middle 2 have 2 each spaced 90° apart. And the furthest 2 have a single gland each. This is so the control distributes to both middle buckets and onto the furthest in a sort of more passive manner.
This is the controls for the 12v solenoid gravity return. A sonoff basic on the left. And a salvaged 12v driver from some old ikea under kitchen cupboard LED strips on the right. This will be the timer and power supply for the return. Working on a loop timer basis. So when the pump finishes flooding the valve will open and allow the water to flow back into the res.
I still need to order a couple more m25 glands for the return feed and another to add a “drain to waste” bit of hose with an inline butterfly valve on to make res changes super easy.
Probably forgot loads but it’s hard to keep up on a phone. If anyone wants to copy or alter for their space you know where I am. Always happy to help
