Dual Root Zone (possible for AP)

[Vlad Jovanovic]

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).

[Tony L]

Yes that makes a lot of sense and is very interesting.  I guess I still don't follow why you are calling it a "fishless aquaponic system" (instead of calling it a "compartmentalized aquaponic system" or a "hydroponic system supplemented with aquaponic water") but that's not really important (except for getting your point across, because I can see many people confused by that but maybe it's just me).  Are you saying it's the biofilter that makes it an AP system?  Do other people have "fishless ap systems" or is this your invention?  I thought aquaponics meant it had fish (or other aquatic creatures) living in the system.

Looking forward to updates!

Shaun Mavronicolas said:

"Your system sounds really interesting, although I'm not quite sure I follow.  You're saying you have separate systems and you use nutrients from the RAS for the AP system?  Are there other creatures in the fishless AP system?  If you have more info up about this and/or pics, please link."

I have not put anything online yet but will shortly.

The plant system is just that... a fishless aquaponics system. So it has a pump, filtration and most importantly a moving bed bio-filter. Yes, top up water comes from the fish side and I am busy setting up several airlift "tea brewers" that will act as mineralizing tanks - so these will breakdown the fish solids and anything else I want to throw in over about 35 days. I will allow the solids to settle out at the end and scoop out this water for my base nutrient. I will pH balance it to about 6.5 with calcium and potassium buffers over the 35 days for my fruiting plants (this is all I am growing in the plant only loop). I grow my leafy stuff in the RAS. I will have several of these going so I can add nutrients every few days to the main plant system. I will also have some non-aerated minerlaization tanks going for the option of gassing off the nitrates as nitrates in fruiting systems are not desirable in large amounts.

Hope that helps until the pictures appear in my album here.

Cheers.

[Shaun Mavronicolas]

Sure Tony... yes, there is no other "term" for this. It is not hydroponics, so a simple next best term for this is fishless aquaponics as everything else is still there, short of the fish as part of the physical water loop. The nutrients still come from a fish system in the same space, the recirculating plant water simply does not return to the fish side.

I am not doing anything "new", all information is freely available on the web. I've gotten frustrated with the "typical" AP approach... I've had no joy growing a large number of fish and plants in the same system. This is mostly because we have 3-4 months of sunshine or usable growing weather a year, so when there is no sun around nitrates quickly wreak havoc and there is nothing that can be done, short of splitting things up.

I am exploring water remediation options to cleanse the RAS water during 8 months of the year when the plant loop will have little effect on water quality for the fish. Keep in mind with all this that fish and plant production is important in a space of less than 350sq ft. I hope to have fish year round with my staggered growing tanks, not the typical once a year harvest you get from most backyard AP systems.

I am derailing this thread which is about dual root zone growing so will end here with these final notes. Dual root zone growing in my setup as I mentioned above is very much like the Earthan Beds Paul has shared on his site, but on a smaller scale. Wicking beds, another place to "borrow" ideas from.  There is much innovative stuff happening all over the place, building on already proven concepts, nothing much new just adapting what is already out there.

[Tony L]

Ah yes, of course, if the nitrifying bacteria is in the fishless system it is an AP system, I get it now.  Thanks for explaining that.  

Where you wrote "in my setup" you have it underlined, should that be a link?

I will report back with my dual root experiments.  I am going to separate the mediums with coco liner, I hope that's not a mistake.  

[Rob Nash]

We discussed this at length at the last Aquaponic Conference and agreed it is called..  Bio-Ponics.

Tom Speraneo was calling aquaponics that long ago.

not a sterile hydroponics system, but a living, bacteria and fungal rich environment...  just like in aquaponics.. but instead of feeding the "soil/media" with fish poops, you choose from a wide range of options. ..and with out fish to kill, you can really have your way with it.    ...i believe that bioponics will play a huge roll in the future of large scale organic productin.. and back yards for that matter. ...and, dare i say.. maybe more than aquaponics.

so, while all aquaponics would be considered bioponics not all bioponics systems have fish.. just some thing to feed the media. ..worms, compost tea, etc.

[Tony L]

Vlad, sorry I somehow missed your reply until just now.  Thank you for explaining that.  I do not currently have too many nitrates, but I meet the rest of your qualifications about being diligent :)  It's no big deal, I was just curious, I figured I better at least know what the "nitrate problem" is.  I just have a hydro system at the moment so I have a long way to go before I bump into the AP nitrate issue!

Vlad Jovanovic said:

So if you have really high nitrates and can't add any more plants, or can't/don't want to get rid of many fish...and are of diligent mind, capable of following precise directions and keeping it up for weeks at a time...and following through...then sure, I could send you those links etc...(I don't mean to sound all high-falutin' about it, it's just one of those process' that will have catastrophic consequences if not done properly).

[Tony L]

That's really interesting.  What you're saying makes a lot of sense, about bioponics becoming more mainstream than AP (both residentially and commercially).  I wonder if anyone has a large and/or commercial bioponic system going yet. 

 Rob Nash said:

We discussed this at length at the last Aquaponic Conference and agreed it is called..  Bio-Ponics.