I’ve decided that recirculating systems aren’t all they’re cracked up to be. Currently I’m running an ebb and flow pot system, standard flood and drain with hydroton, and previously, I was growing in coco with drain to waste.
Initially, I had thought that reusable media would keep my costs low, and that with a recirculating nutrient solution, it would save on water and nutrients. While this is partially true, I am underwhelmed by the water savings (because you have to regularly change the reservoir anyway, and plants actually drink a large portion of it). Also, it increases the pH control requirements, adding more pH down into your nutrient. It shares pathogens across plants, and feeds an ever-changing nutrient profile that degrades within 2 weeks.
Hydroton is fairly reusable. However, in the past few grows, I feel that it has also degraded. Mind you, I’ve ‘cleaned’ it nearly 10 times by now, but it appears to cling onto shit and also cleaning products that eventually cause problems as well.
I want to go back to top feeding. I feel that it’s good to keep an overall flow of nutrients downward and out the bottom of the pot. Last, I have always wanted a system that allows the plants to decide when to feed themselves.
Here’s what I’m starting with:
It’s your typical ebb and flow bucket system. Normally you fill into the control bucket, which pushes water up through the bottom of the bucket until the nutrient level turns off the float switch. The nutrient solution floods the pots for a period of time, and then the solution is drained by pumping the nutrient back out of the control bucket into the reservoir.
And here’s my conversion plan (perfectly drawn in MS paint to a 7 year old’s standards):
Everything still remains automated like the ebb and flow; however it takes some ideas from hempys. Rather than filling the pots with hydroton, I will first put a hydroton layer on the bottom to elevate the base where the fabric pot will sit on top of. The reason for this is to add a little more volume of nutrient solution that will allow some wicking and dispersion of the waste.
On top of that, I will put a fabric pot and then maybe an inch or two of perlite inside at the bottom. I think I would like the coco coir to be just slightly above the water level, and the perlite will allow enough wicking to account for the hysteresis of the float switch.
Finally, the high drainage coco mix goes on top of that. The reason for using 50% perlite is so that the media drains quickly so that the float switches will be responsive and not over-saturate. Also, this allows the roots to grow densely in small pots, which I have had good success with.
They will be top fed using dripper stakes, like the usual netafim dripper assemblies or the ones from floraflex (both inexpensive). I am not quite certain what flow rate to use. I’m considering slow drippers ~0.5gal/hr so that they will not feed too quickly and give plenty of time for drainage.
In this scenario, I would probably set the system to feed all day (although it will stop once the float switch reaches level and stay off for many hours at a time). And at night, it would remain in the ‘drain’ phase the whole time lights are off – though I would disconnect the drain pump.
Like a hempy bucket, the plants would consume the nutrient in the coco, and then wick up some nutrient from below. Once enough has been consumed, the nutrient level would drop and cause the float switch to turn the pump on. Then the drippers would rehydrate the coco, and drain enough to raise the float and shut back off.
The main advantage is that the plants are now feeding themselves. The timer is irrelevant, and the plants can claim more nutrient at precisely the time that they require it. The fabric pots also act as a filter for the coco, so that it doesn’t clog up the lines. Waste accumulates in the areas below the pot and at some point is likely to become ‘hot’. I imagine that maybe once a week, I’ll just need to drain the control bucket completely and let it refill.
That’s all for now! I’m going to decide what I need to make the retrofit and snap some more pictures soon. If anybody has any other good ideas or input, I’d be happy to hear it.
Also, on a side note, all of this could be done very inexpensively with a cat litter bucket a cheap float switch and a timer. The $250 active aqua control bucket is really overkill here. You can buy a 6-bucket expansion bucket kit for about $100, so with a little creativity this can be a fairly cheap method. I’ve been racking my brain over a simple way to make a plant-led feeding system, and I’m optimistic that this will work.
