Here is an idea that I believe if done PROPERLY could be used in an AP system with fish…[edit* as of this writing, it has been used in dozens of systems with fish]. I first described what I've done in Wil’s ‘Medicinal Plants Any Luck’ discussion (there is some encouraging feedback from people I respect there, and other ideas we bounced around which might be worth checking out)…
The deal here was that once my AP system is up and running, I wanted be able to cater to the needs of specific plants that may have nutritional requirements that a brand new system might not be able to provide (so called ‘heavy feeders' like tomatoes, corn, cucumbers, for instance). Patience, I've been told, is not one of my strong suits. And I don't want big huge tomato plants with no tomatoes, or even no flowers, stuck in a nitrate induced perpetual vegetative twilight-zone of just green leafy growth. Yet pouring different nutrients, or nutrient products into your AP system (like P-K, “bloom/flower” type products) may not be advisable for a number of reasons discussed at length elsewhere. So what I did was the following…
Research shows that plants in nature tend to specialize the function of their roots. To make a long story short, we’ll divide the rhizosphere into two categories: upper roots, and lower roots. The upper roots tend to spread throughout the top soil specializing in seeking and up-taking nutrients, while the lower roots go downward seeking out moisture, specializing in water up-take. Using this concept I’ve taken five 13cm net pots (for hot peppers, but you can go larger for tom’s etc…) and set them up in the following way...
Fill the bottom half of the net pot with hydroton (rinsed, presoaked). Put a thin layer (5-10mm thick) of rockwool on top of the hydroton. (I have a rockwool cube and a sharp ceramic knife, so this was easy, but you can tear of pieces with your fingers as well). The whole purpose for the rockwool is to act as a barrier between the upper and lower zone of your net pot, so make sure all the hydroton is covered.
Fill the remainder of the net-pot with a mixture 13/perlite, 1/3 vermiculite, 1/3 cocco coir. To this mixture I added about 10% worm castings a handful of hydroton, to help with compaction, and about 5% Zeolite (I might forgo the Zeolite in an AP set-up though).
Then I poured water into this top portion and noted when water started leaking down into the hydroton. This way you will know what the absorption capacity of the upper layer is. Later when feeding your plants use slightly less than this ultimate holding capacity amount. Three small weekly feedings is probably better than one large one. This is an extra pot that I took a picture of...
If you had some screen material you could line the inside wall with it, but probably not necessary.
I planted my 3 Habeneros and 2 Hungarian Wax into the net pots. They have been placed into an aerated DWC bin. The reservoir holds only water (no nutes) and the roots have begun to dangle in it. There is about a 1" air-space between where the rockwool layer is and the top of the water, so that the upper layer doen't get too moist from over-wicking. This air space might also help with oxygenation of some of the roots.
Every third day or so I feed a solution of liquid home made nutes (but you could use whatever type you wanted, orgaic hydro store bought, mineral salts etc)…I pour only enough solution as the top mixture will hold so as not to contaminate the reservoir (or an AP system) with nutrients. They are growing like mad thus far.
In an AP setting the bottom roots would be exposed to both moisture and mostly nitrates, while the upper to whatever you wanted (though I imagine and K, Mg and P...would be among the prime candidates...and perhaps P if your system is real, real new.but P shouldn't ever really be a problem in a well fed AP system).
As long as you didn't over saturate with your solution while top feeding your plants, you should be able to keep any nutrient contaminants out of your AP system. Another benefit, would be less root mass to deal with in your grow bed (which is where this idea evolved from anyways).... I had originally planned on using 'huge' net-pot-bucket-with-drilled-out-holes filled with hydroton to help contain some of the root mass of the tomato plants, and make it easier too get it out of the grow bed when the time came. Reclaiming and re-using the hydroton would also be simple. Since I am relying on my 8 IBC media beds to pre-filter the DWC troughs, the last thing I need is a root bound anaerobic bed to deal with because of a couple of tomato plants. This method can address both the nutrient issue, and may help keep the more monstrous roots contained and more manageable. (Less maintenance to the grow bed).
Nope the net pots are far away from the bottom of the tub...
The tub is actually pretty deep, as i wanted to be able to accommodate downward root growth. The 2" polystyrene raft was cut to a perfectly snug fit so it doesn't sink/rise with falling water levels. There is an air space I try too keep within an inch or two from the rockwool line. The the level of the water is an inch or two below the bottom of the styrene. the upper layer of the net pots seem to get too moist for my liking if the water level is all the way up to the bottom of the raft...just too much wicking IMO. The water is just str8 water "hard" from the aquifer, having been pH adjusted with HCL (so not entirely nute free as there is Ca2+ which was released from the carbonate/BiCarbonate form that exists in "hard" water, when I added the acid. there is also quite a bit of magnesium in my well water too. And more than likely, some other traces of things. (Cu from the pipes, a little Fe also from the mains pipes at the pump etc)...I added a little bit of Iron to the resevoir... Other than that...nothing. All N-P-K and additional secondary elements are added to, and hang out in the top-mix of the net pots, and don't make it down into the reservoir.
There is a Heto SK9830 aquarium air pump and two AS8L medium pore diffusers rated at 0.35cfm providing aeration. (Might be a tad much, but my personal belief is that you can't really have too much O2 at the rootzone. And people always seem to skimp on the O2 with less than stellar results).
No dumping and changing of water. Just topped up.
Yes there are many many ways to skin this cat...flood and drain DWC etc...but this was easiest (space wise, for me, and I'm partial to DWC anyways. Especially since I heat my house with wood (dry-ish air) and the heat of the lamps blabla...this way the plants have a steady never ending supply of H2O and less 'fail points' should electricity cut out.
No, I did not really 'invent' anything, real scientist discovered that plants have specialized roots in this way, I more or less recently discovered this fact, and started playing around with it with what materials I have and in a way that may suit my eventual AP purposes. I am sure others in hydro have done the same, but I do not have any access to any hydroponic research regarding this application unfortunately. But I am sure it is out there, as when I asked a someone who works in the hydro world whether this dual root zone thingy would better grow plants they said "it's hard to argue with some of the research...but that in practicality it's probably not going to yield noticeable results..." from other standard hydro methodologies... which let me know at least that it has indeed been researched. Besides, my unspoken intent was for AP. At this point I don't really care if the plants will grow faster than in a single root zone set up within the same system, I just want the nutes separate. I'll do this again with mineral salts solution as top feeding and take EC readings from the reservoir just to make sure of things.
Wait, on second thought I DID invent this, so every time you click on this discussion you will be charged $5.00USD :)
Thank you Jon, I do appreciate it...
Yep, in this sort of bin/box set up, it would seem a good way to try out different nutes you made (or bought even) and keep the other variables to a minimum. Hehe, that puny one in the front there, won't stay that way for long (and will probably be kicking my ass with super spicy pods soon enough)... I just recently added him to bin (though he was re-potted dual root zone style when all the others were). I had originally delegated him to the orphan/holding bin. (It's a sad sad place, where they await various bad experiments :)... Out of the three Hab seed's I had, all three came up, but one was super slow growing. Stunted. I had two more healthy wax's, and one really f***ed up one. I chose to put the Quazi Motto messed up one in the bin. It had some sort of deformity or deficiency right off the bat. I mean as soon as it came out from seed you could see something wasn't right. Kept on growing just fine, putting on weight. But the leaves had these weird metallic flecks thing going on, and holes would form all by themselves between the veins of some of the leaves. Normally I would have tossed it without a second thought, chalking it up to just 'a bad seed'. But then I thought, well wait, what was it that made this seed bad? Is it a genetic thing, or was the non genetic seed material lacking in some element(s) or another. If the later, then maybe this would clear up as the plant grew and those things were provided. I half thought that it would... They started putting out shoots, and well, they were all pretty messed up. It was like looking at a fractal, almost all the new leaves showed the same deformity in the same places in almost the same shapes. And holes like the one pictured above. So I tossed it the other day and put in 'the little guy'.
Very nice! Can't wait to see what you do with the PL-L's...Man Ancho's seem to take forever , maybe now with the greenhouse I'll be able to extend our season here enough to get a decent harvest (still have some seeds).
Yeah, they are quite a bit quicker now than they were this past spring/summer in the ground, or even potted. Though even then they are by no stretch a 'slow growing pepper', which is good for our growing season here. Lots of O2, god temps, and really good lighting (PL then MH) probably has alot to do with it too :)
There are 6 or 7 more flowers that opened up since then.