I decided to do a bit of a root autopsy on the side-by-side 1L SIP plants I recently harvested.
One was my "gravel bed" version, which was essentially the reservoir filled with hydroton clay balls to a bit above the drain hole, and the other, the "cave" structure which mimics the bucket-in-bucket design with the central connector pot and the larger reservoir.
I'm going to let them dry more to see if I can tease the soil out and better compare the root structure but I have some preliminary take aways I thought I share.
First the harvest weights were essentially identical so either design in the end worked very well. I did have an N issue midway through veg on the gravel version so that one stalled out for I think 2-3 weeks while I worked on a solution so that very well may have held that version back in harvest weight.
The gravel bed version had very dense and fine feeder roots essentially from maybe an inch below the top all the way through the hydroton to the very bottom, and looks like that's probably true of the interior of the pot as well. I may cut the rootball in half vertically and see.
The cave structure roots seem to be a mixture of feeder roots and water seeking roots and are no where as thick as the cave version. You'll recall early on in the grow I was surprised at how the initial roots found the connector pot ok but putzed around for a while before making their way into the water itself. The roots eventually populated that connector pot and short bits did sneak out of the drainage holes a bit into the reservoir area but did not extend much into it.
I was surprised by this as I kept the reservoir in both filled every day after the first three weeks or so and thought I'd see a bit of a hydro root-thing going on. But, not so much.
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And now, for the larger 2G bucket versions that have now made it to flower, I modified the designs a bit.
The first two are the bucket-in-bucket design (cave structure) again albeit all within a single bucket because of height constraints (I built a false floor from a bucket lid to separate the soil from the reservoir and fed the connector pot down through it).
The next two are closer to the
Commercial version that
@Buds Buddy is using. For these I'm using either food storage containers or pasta strainers inverted to serve as a dome to keep soil out of the air and water reservoir. I have the fill tubes going right into these domes/voids.
The first plant in the second (dome) version is only in veg and I can't see the roots in these buckets like I can with my 1L take-out containers but I think I'm having the same issues with roots as I did before. The dome version plant seems to be drinking more and sooner that the bucket-in-bucket design, but I won't know until the current veg plant gets harvested, and that's looking like year-end at best.
The dome version is also easier to build with fewer parts and only needs a single bucket so is a more efficient design. On these, like the commercial version, the soil drapes down around the dome and sits in the water. I was concerned about my organic mix going anaerobic sitting in the water all the time so I built a version of this in a 1L version and I don't seem to be having any issues after a few weeks.
Assuming this continues, I wonder if I would be able to feed my liquid KNF and Jadam extractions via the reservoir since the microbes needed for delivery will be in the soil sitting right there in the water. That will be something I'll test in the 1L version in the coming weeks.
In conclusion, I am very pleased with the above ground results from both versions but think the dome version is where I'll probably stay. It is easier to build, gives a better feeder root structure and may give me the ability to feed with my extraction fertilizers.
But either way, these things rock!