SIP Club - Getting Hydro/Coco Results In A Soil Based Medium

[Fenderbender]

When I designed my Triforce SIP, I studied up on oxygen permeation into soil, and the need for roots to have access to oxygen—what is called "root respiration". This is necessary for the biochemical processes that create the cellular energy that drives both water and nutrient uptake in the roots. In other words, roots love oxygen. If they don't get enough, because the soil is impervious to air, or because of too much water in the soil, this shuts down growth and also invites disease due to the anaerobic environment.

So in my design I maximized the surface area of the air-to-soil interface, by putting a lot of small holes in the domes, both on the top and on the sides. I call these the "air/water vents". The holes have a dual-dual purpose—air inflow/outflow and water inflow/outflow. As the reservoir level goes down, more holes provide air to the root zone. When the reservoir is filled down the tube, the water level in the domes rises, pushing air into the medium.

Another very important dynamic is the composition of the soil medium, which must accommodate good air flow. This is why it's very good to use lots of coconut coir, and a good amount of perlite as well. Keep in mind that on the microscopic level, the soil medium has lots of air space between the solid particles. The root filaments inhabit these spaces where they have plenty of access to oxygen.

More photos and details about my design HERE.

The heart of the Triforce SIP—three domes D1, D2, and D3. Note that there's a friction fit on the fill tube connection to D1, so that it can hover in place in the air pocket. When the bucket is filled with soil and in use, the fill tube can be adjusted slightly up or down no problem.

#2 food grade HDPE plastic yogurt container.

The shaded area is what I call the "R zone", where roots have access to the saturated medium in the reservoir, and also have access to the air vents. This R zone is much larger than in other SIP bucket designs, and provides a large wicking area as well.

So far, so good...

A CBD clone recently transferred to the flower house. This is the first plant I've flowered in a SIP. She's drinking very well and doing great. The reservoir holds about a gallon of fertigation water, which gets used up in 1-2 days.

HI-BISCUS comparison grow, Triforce SIP on the left. I'm at the point where the reservoir needs to be filled every 1-2 days—fertigated down the tube. The big lesson in this first SIP grow was that fertigation should have been started at 2 weeks into the grow.

But my point is the roots you get at the bottom of a sip are not using that oxygen as they are incapable of it. As that's the switchover that happens when you plant into a SIP roots change to aquatic roots.
But to warden off bacteria might make sense, like an airstone in a DWC you don't really use that to provide oxygen to the roots, the roots can breathe from the water, you use that to keep bacteria from forming.

hmm yeah I'm currently operating with no holes, but previous grows as well but then I was using a lot of pebbles in between the water channel and the soil.. I even taped the four last time that connect to the reservoir as roots used to congregate there to try to get into the res. I had planned on making the holes if I switched to filling the SIP completely with soil but totally forgot.

 

[Fenderbender]

And so far these plants haven't complained once, but knock on wood I guess?
Day 36

 

[cbdhemp808]

But my point is the roots you get at the bottom of a sip are not using that oxygen as they are incapable of it. As that's the switchover that happens when you plant into a SIP roots change to aquatic roots.

Hmm, two things: 1) water roots still need oxygen and they get it from dissolved oxygen in the water, 2) the feeder roots closer to the surface are getting oxygen from the air pockets below and also from the surface. Likewise both water roots and feeder roots are also getting fertigation nutrients—water roots directly from the rez, and feeder roots because of the wicking.

Since the reservoir is an ebb and flow system, with a full-of-water state and an empty or almost-empty state, the deep roots are getting air directly that way. Also, in a SIP with an R zone like mine, the deep roots are going into saturated medium, and with ebb and flow, that medium has trapped air in it.

Also, the reservoir's water surface is exposed to air, inside the domes, and the water absorbs oxygen from the air right at that interface. As the reservoir level drops, that water-oxygen layer reaches all the deep roots.

But to warden off bacteria might make sense, like an airstone in a DWC you don't really use that to provide oxygen to the roots, the roots can breathe from the water, you use that to keep bacteria from forming.

Yes, the SIP with its air pockets provides air throughout the system, keeping it aerobic and keeping anaerobic nasties away, including pathogenic fungi. (Ironically, the identical HI-BISCUS clones I'm growing in my comparison grow came from a grandmother that suffered from a root zone pathogen that I successfully treated.)

hmm yeah I'm currently operating with no holes, but previous grows as well but then I was using a lot of pebbles in between the water channel and the soil.. I even taped the four last time that connect to the reservoir as roots used to congregate there to try to get into the res. I had planned on making the holes if I switched to filling the SIP completely with soil but totally forgot.

My SIP's dome air/water vents work in concert with the "R zone"—i.e. the space in between the 3 domes. I think the R zone is super good, because you have a lot of space there for roots to directly reach the saturated medium. The holes are then distributed all around this area, with the 3 domes having holes on top and on the sides.

 

[Fenderbender]

Yes agree they still need oxygen but they can get it from the water, these roots don't like a wet/dry cycle as you're kinda suffocating them when they get dry.
But yeah the bacteria stuff, I could run my DWC which was a hydro dripper/dwc combo for a long time without an airstone as well the res was huge lots of water and it got dripped over pebbles and back in the res again. Only when the root system was getting too big a bubbler was required to keep things from yellowing, I guess at that point if I'd replenish the water daily it would also not be necessary. my point being that roots can survive very fine for a long time in water without any speciality or air, just well the water needs to be refreshed.

And well here water doesn't sit long it gets absorbed in a couple days and replenished so there's always fresh oxygenated water available to the plant. And yes air can get in and out the reservoir.
But the bottom of the pot with soil is pretty closed off from the world so yeah don't know what's happening there.

 

[cbdhemp808]

Yes agree they still need oxygen but they can get it from the water, these roots don't like a wet/dry cycle as you're kinda suffocating them when they get dry.

Correct me if I'm wrong, but I think you are saying that an air space above the reservoir is not necessary in a SIP, and that the fill tube and the drain hole/tube do provide air, although that air really isn't needed for the roots to be happy.

I think I disagree with this, but the design of the SIP also matters. I see two main design types for a SIP—the kind with a large R zone (like mine) where you've got lots of roots in saturated soil in the reservoir, and the other kind with a small R zone (e.g. GroBucket) with lots of vents in the top of the dome allowing some access of roots directly into the reservoir.

I think your argument holds some water (pun intended) if we are talking about the roots-directly-in-the-water type of SIP, although I really don't know much about hydroponic systems. In the case of the large R zone, with roots in saturated soil, I think you definitely need air and an air space in that case.

Another factor is simply the design of the dome and drain hole/tube—i.e. a good design automatically has an air space above the drain hole, based on the size of the hole. For example, if you've got a 3/4" drain hole, you automatically have a 3/4" air space.

Regarding deep roots drying out... that's definitely not what I'm shooting for with my SIP. I'm now filling the rez when the level gets to about 1 inch. It's completely dark and cool in there, with high humidity. I think the roots are fine with this.

But yeah the bacteria stuff, I could run my DWC which was a hydro dripper/dwc combo for a long time without an airstone as well the res was huge lots of water and it got dripped over pebbles and back in the res again. Only when the root system was getting too big a bubbler was required to keep things from yellowing, I guess at that point if I'd replenish the water daily it would also not be necessary. my point being that roots can survive very fine for a long time in water without any speciality or air, just well the water needs to be refreshed.

It sounds like the water was circulating and tumbling over rocks and getting some aeration that way.

And well here water doesn't sit long it gets absorbed in a couple days and replenished so there's always fresh oxygenated water available to the plant. And yes air can get in and out the reservoir.

But the bottom of the pot with soil is pretty closed off from the world so yeah don't know what's happening there.

I still think the air space is a good thing, but I agree that a regular nursery pot is closed off from air flow. Indeed, I've occasionally had problems with root rot even in well-draining pots. It can kill a plant almost overnight.

 

[Fenderbender]

No the airspace is still there in my pots, there's just no holes going from the pot to the reservoir.
Like if you look at the Grobucket insert that top is perforated and under that perforation is the airgap with the water.

Mine's like this, there's water channel with some slits. Air can go down the tube, or down the sides as there's a slit where the bottom reservoir meets this top half. but yeah that air only connects to the water not the soil since there's no holes..

 

[cbdhemp808]

OK, I see... Elho Greensense Aqua Care Square. So it's basically a plant pot with a 1 gal reservoir, and the clay balls wick the water up. Looks like you've got no air coming in via the tube, because the tube touches the bottom of the container. But there is an air space. How much soil does it hold?

 

[Fenderbender]

Yeah that's it, these are 15L, got a bigger model as well.
Well the tube has a sideways slit but yes it's closed off by water, but water touches atmosphere there and in the reservoir as well there's gap and all around you could pour the reservoir out between the slit where the two parts meet so air can get in there as well.
And I didn't use the pebbles this time and filled it all with soil as that gives me a lot more nutrients in the can, and I also wanted to see if that performs differently.