Ok – the previous hydroponic seedling setup was an unmitigated catastrophe.
I don’t think the pumicy stuff drained properly so there was a kindof seedling-drowning situation going on… and I don’t think pumice is such a crash-hot medium in any case because… it floats… so it’s constantly shifting. One big advantage though… if you want to separate the seedling from the medium, you just overflow everything… the pumice floats away.
So anyway, Only a handful of the seedlings survived, so I went for an eb-and flow system.
Which actually works pretty well.
You can get these plastic bins from the gazilla-mart… where there are deep ones and shallow ones, and they fit inside each other, so you can cut a hole in the bottom of the shallow one, and a couple of holes in the side… just below the top of the plant-growing-medium… then get a little fish-tank pump to squirt water straight up. I jammed a couple of extra pots in the gaps to stop everything floating up and tipping over.
Normally Gravity never misses a chance to fuck you up, but when you’re underwater, it’s kindof the opposite – which can be just as bad and it’s actually quite disorientating if you’re accustomed to having issues with gravity being up the other way.
Let it fill up for a couple of seconds… then let it drain. None of the joints need to be terribly tight because the pump is quite strong. I cramed a load of tangled up wire down the tube, which aerates the water, and stops bits of stuff going down the tube when it’s draining.
Basically works like this:
I’ve made a little automatic timer for the pump… basically an arduino on a long loop, attached to a relay. Dead simple… in fact using an entire arduino seems like overkill, so I bought a miniduino of ali-express… which is still overkill, but it’s overkill in a smaller container.
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I think one of the problems you had with your first set up would be insufficient aeration. The roots need oxygen to survive.
With your ebb and flow system you could go for a loop siphon or a bell siphon. I made one out of a loop of garden hose. With that you can have your pump running continuously as long as the siphon can get rid of the water faster than the pump is pumping it in. It can take a little bit of fiddling but relies on less components in the long run.
If I could make a suggestion it would be to go for an aquaponics system. You would need to make the system a little bigger to be stable, but you end up with wonderful results, plus fish!
Sorry for not responding to your previous comment! I didn’t click the notify box for some reason.
The Aquaponics things is a step some way down the line…. need to get plants to survive first :) I really like the idea of closed-systems though. It’s a space-ship thing.
I looked at bell-siphon systems… decided to go with electronically switching the pump on and off… at least partly because another long-term goal is to have sensors controlling a bunch of different environmental variables.
I’m not sure that switching on/off is good for the pump… but really it only needs to be on a couple of minutes a day (throughout the day), rather than 24/7.