Aquaponics - Externalized sequencer

From time to time I need to empty my head of all the luggage I carry around in there. A while ago I did just such a thing when this idea came out.

This is the second design (here is the first) of mine for a grow bed flooding sequencer. The aim here is to fill each grow bed in turn so as not to empty the fish tank and leave your fish walking more than they like.

Picture an inverted rotating lawn sprinkler with all but one of its arms cut off and blocked. Mount that over a bucket,with a drain going back to the fish tank, and a pipe for every grow bed you want to fill. The drain is to catch the bit of water that misses the tubes, as the sprinkler arm is moving between tubes, and to catch any small leaks the sprinkler has  from the moving seals.

The aim is to have it rotate from one tube to the next, stopping for long enough to fill the grow bed that's connected to each tube. The grow beds take it in turns to get filled, and as one is filling, another (or others) are emptying back into the fish tank.

Make one of these for each tube. The bottom of each tube is connected to it's grow bed and the apparatus is mounted at the same height as the grow beds, so that as they get close to their full depth, the float begins to rise.

When the float rises enough the hook lifts above the point at which it restricts the rotation of the sprinkler arm, and the arm moves on to the next tube.










When you first set it up, leave enough extra length on the downwards bit of the hooks so you can file a bit off to fine tune it to trigger at exactly the correct height. Or you could use a nut and bolt arrangement to make it adjustable.

It should also be possible, to some degree, to accommodate grow beds at different heights by increasing the length of the tubes, placing the floats deeper, and extending the pole that holds the hook.










Feel free to repost these images elsewhere, but please leave the "120 things in 20 years" caption on them.


[edit from the future - There is some additional material on sequencers. Readers might find this newer version in a post titled  The Bullwinkle sequencer build of interest. It's a better design, and only costs around AU$15 to build with off the shelf PVC components]