auto fill bucket question

Hello everyone i was watching the seemorebuds2 and 3 videos and was checking this guys bucket system and really dig them. Now here is what im aiming at doing. I have the nutriculture NFT system and want to remove the tanks and put in place gullies for the water to flow from the bed into a bucket which will have a pump inside and what i need it to do is to come on when the bucket hits a certain and pump the water back to the main reservoir.

Now my question is what are these buckets called? in the video they were all black with pump and water level stuff inside of them. It is massivly urgent that i find out where to get some. Links and any input is welcomed. thanks

bump............