When testing out a new multi-grow-bed system, for the first time we connected three grow beds to the same drain pipe. Previously, we had only connected two grow beds to the same drain pipe. These drain pipes always slope downwards to the fish tank from the grow beds. With two connected, we had no problem with them doing their siphoning when needed, regardless of timing. But, with three connected we found that they interacted, thereby preventing all three from cycling at the same time. At first I thought that we would have to either provide a separate drain for the third grow bed or increase the size of the drain pipe.

The smaller drain pipe helps pull the water from the grow bed during siphoning, so I didn't want to increase its size. I then realized that this was a blessing in disguise, as it didn't allow all three grow beds to dump their water into the fish tank simultaneously. Once the first grow bed to siphon was finished while the second grow bed was still siphoning then the third grow bed would start its siphoning action. They all just synchronized up beautifully, each taking its turn with only two grow beds siphoning at any one time. The third was just queued up ready to began its siphoning action as soon as the pressure in the drain pipe was reduced by one of the other grow beds completing its siphoning action.

Oliver