Sub Irrigated Planter (SIP) with Living Soil, following the horizonal method?

[green_machine]

O.K. here we go with version 2 of my SIP.

 

Be prepared I outdid myself on the artwork this time

 

 

 

 

I have borrowed heavily from Slims set up here but I like this and it has some distinct advantages over the original set up. First, let's start with a breakdown from the bottom going up.

 

The very bottom will be a 2'X4' flexitray. I selected these as I believe they are the deepest trays on the market, if anyone knows anything deeper let me know.

 

I will install the aquavalve on one end of the tray and surround this with some sort of cage to protect it from the weight of the bed above. I was thinking about making a cage out of plastic egg crate but I might need to find something more heavy-duty. I also need to confirm the height of the aquavalve as it will need to sit below the level of the top of the tray.

 

I will surround this area outside of the aquavalve with lava rock and cap this off with horticultural grit to give me a level surface for my bed.

 

For my grow bed I would like to go with a 2'x4'grassroots fabric bed. The bottom of this would act as my membrane so I would no longer need the terram fabric. this bed leaves me with very little clearance around the tray or tent so as I mentioned above I need to check that the aquavalve would fit below the level of the tray so that my pot would sit level. If I am unable to use this bed I could swap to 2 larger fabric pots but would lose a significant volume of soil from this.

 

The layers in the bed would stay roughly similar, I would start with a layer of sand at the bottom.

 

I love the idea of replacing the lake clay with akadama, this seems like a much better option (I'm going to say damn  the expense but my wallet is angry at you @BilgePump ) Do you have a recommendation on size/ do I need the super small stuff

 

The rest of the bed would stay the same, with wood chips as a carbon source, followed by my living soil and a mulch layer on the top.

 

So what are the benefits of this system over the original, well there are a few as far as I can see:

 

1) The water reservoir is stored outside so I can keep a pump in it to keep the water moving and oxygenated.

2) With the reservoir outside the tent I can make it much larger so could go much longer without having to worry about watering.

3) If I find my bed is getting too wet I can easily control the moisture levels by shutting of the flow from the reservoir.

4) I get a bigger grow bed using this method

5) I don't have to sacrifice growing space for my reservoir.

 

So what do you think? Is there anything else we can do to improve on this?

 

[NormanNugget]

@green_machine

 

Not sure these are improvements, but a couple of suggestions to consider.

 

1. The Aquabox Straight I mentioned above comes in a plastic housing which might do to act as the cage in this configuration

 

2. You can essentially buy this as a 1’x3’ kit. Google ‘Autopot Grassroots Sub Irrigation System’ and you’ll find it. Maybe you could stick two of these in side by side

 

3. I think you want to maintain access to the Aquavalve as it seems they have some points which may get blocked and need cleaning. All of the Autopot

systems leave these accessible. I wouldn’t want to be trying to haul that

bed off of the tray to get to the Aquavalve!

 

Keep up the good work. I’m selfishly hoping you nail this so I can steal your idea in the future once I find a suitable space

[BilgePump]

6 hours ago, green_machine said:

recommendation on size

Id go with a bigger grain , its very porous stuff so will wick very well regardless.

 

I really like design 2 bro , looks sweet

 

[MindSoup]

7 hours ago, green_machine said:

 

So what do you think? Is there anything else we can do to improve on this?

 

 

Yeah you'll definitely need some way to access and remove the aquavalve as it will need cleaning/checking quite regularly, even just limescale build up will stop it working eventually. 

[green_machine]

@NormanNugget @MindSoup

 

Thanks for the advice on the aquavalves, it is helpful.

 

I had to think about the best way around this and the simple solution would be to swap from a 2x4 bed to 2 x 20 gallon pots. These are 51cm in diameter and would give me more than enough space to fit an aqua valve in the middle of the tray with easy access and a pot on each side.

 

In fact. I could swap from a single tray to 2 x 59cm square trays, one for each pot and still have space for an aquavalve in each tray. This does seem to have greater biosecurity, i.e. an infection in one bed might not necessarily infect the other.

 

However, the volume of soil in these pots is considerably smaller than what I would gain from a bed, almost by 100l.

 

I wonder if there are other, smarter alternatives to an aquavalve, that would let me keep my grow bed.

 

I have been wondering if I could use a set of wifi moisture sensors (something like the ecowitt soil sensors) and a Wi-Fi-controlled solenoid switch to control a feed line on a reservoir.

 

I am unsure if the sensors would be able to sense moisture in the gravel layer but I could always include a sand layer in the tray and this should be enough for the sensors to work. This way I could monitor the moisture levels within the tray and as it drops I could turn on the switch for the feed line from my phone.

 

Does anyone have any experience with systems like this or know anyone who might have that they could tag to advise? 

[MindSoup]

29 minutes ago, green_machine said:

In fact. I could swap from a single tray to 2 x 59cm square trays, one for each pot and still have space for an aquavalve in each tray. This does seem to have greater biosecurity, i.e. an infection in one bed might not necessarily infect the other.

 

That would work well, I would also agree that desperate trays are a good idea. Would ensure both pots get what they need while also stopping them swapping any potential diseases. A single 100L bed would definitely be better though. 

 

31 minutes ago, green_machine said:

ecowitt soil sensors

 

Really aren't all that accurate IME, I wouldn't beat to rely on one for your purposes. 

 

Could you not just make the bed a bit smaller than the tray and then have the valve to one side of it? You could even notch out a corner depending on the construction method of the bed. 

 

[green_machine]

The bed is a standard 2x4 grassroots pipe-supported bed, while it is slightly smaller than the tray the clearance is only around 3cm  so not enough for an aquavalve to the side.

 

I was looking online for other wifi based solutions and I came across this

 

Tuya Water Level Sensor Wifi Smart Home Leakage Flood Alarm Controller Meter Pool Vape Tank Flow Detector Leak Protection Switch

 

It seems to be a water level sensor, that is used in irrigation systems. It can set minimum and maximum water levels and it can control a feed line I believe.

 

I wonder if something like this could work. I could set a minimum and maximum water level for the tray and this could provide water whenever it reaches the minimum level and stop when it reaches the maximum.  This one is a cheap Chinese-made controller but there must be alternative versions of this out there.

[MindSoup]

Any kind of sensor/valve will need to be accessible for cleaning purposes. So I guess if you can fit that in beside the bed it could be worth a try. Unfortunately I've not seen anything similar from a reputable manufacturer and I've been looking myself for quite a while. I'll be very keen to hear if you don't anything or how you get on with the Chinese one, some of them are actually really good. 

Edited May 21 by MindSoup

[green_machine]

what's your electrical knowledge like @MindSoup

 

I don't mind taking a chance on one of those Chinese sensors but I can't really get my head around the wiring diagram as I don't need all the functionality. I know you are pretty handy in all things DIY so I wonder if you could help me work my way through this.

 

Here is the diagram:

 

 

I don't think I need terminals 9-12 and I would use connections 7-8 to control my feed, ideally, I would use a solenoid to open or close a gravity feed line.

 

The aim would be to set up the sensors at the required levels in my tray and when the water level dropped to the 25%position the controller would kick in and refill the tray to the 100% level.

 

Does this make sense and does it seem possible?

 

 

Edit 1 - Errrr on second thoughts maybe I do need connections 11-12, these look like the power supply for the controller

Edited May 21 by green_machine
correction

[MindSoup]

To me it sounds like you've got the right idea, I reckon you might get away with just the 6 and 2 sensors to monitor the levels maybe a 75%  as well to give it a bit of warning and reduce the risk of over filling the tray. Then as you say 7 and 8 to control the water feed. The bit that doesn't immediately make sense to me is the control of the water feed, what voltage 7 and or 8 put out would change what kind of solenoid/valve you might be able to use. It's the sort of thing you could ask the seller/manufacturer, but my experience with trying to get accurate understable info from Ali express sellers and the like hasn't been great if I'm honest, they have a habit of telling you whatever you want to hear or just not making any sense at all.... 

 

I do like the look of it though and if it's well made and works properly I can see it being a super useful bit of equipment. I dare say if it's cheap enough just buy it with the intention not making it work. It also looks like some that someone who knows about Arduino/raspberry pi could quite easily build DIY if you fancy that avenue. 

Edited May 21 by MindSoup

[NormanNugget]

I would have thought the simplest solution would be to use the aquavalve (no electronics etc). All you really need to do is ensure you have access.

 

So you could cut a hole in the bottom of the bed and fit an access tube that sits around the aquavalve. Maybe just a pipe or similar with a big enough diameter that you can get your arm down. Then leave enough additional feed pipe to the aqua valve so you can pull it up for maintenance.

 

No real idea how deep the bed will be to see whether that’s feasible..

[MindSoup]

That's actually a really good idea, section of 220mm (ish)  pipe with a hole cut in it to get the valve in/out, put that in first before the bed and the soil. You'd need some cut outs around the bottom so the water to could pass through. 

Edited May 21 by MindSoup

[NormanNugget]

If you search for ‘stop tap chamber’ or ‘duct access chamber’ you can buy these assemblies. Basically a miniature manhole which I’m sure could be easily adapted to suit an aquavalve and the depth of the bed.

 

Now this might sound insane, and I’m not up on my Duplo prices but… you could

build exactly what you want as an access shaft out of Duplo (or Lego).

 

Also, if you have a bit of extra length beyond the tray in the tent, you could just look at hacking together an autopot into the side of the tray so the aquavalve chamber sits out to the side. Essentially just making your own tray2grow.

[green_machine]

I agree that I was overthinking the solution, there is no need for fancy electrics what I can do is use 2 x 1'x3' beds in my 2'x4' tray.

 

This would mean I have 2 free 1ft square sections in opposite corners. I could place an aquavalve in each corner and have plenty of space to access it and I could run both valves from the same reservoir.

 

In terms of soil, each of those 1x3 beds holds around 90 litres so overall I only lose around 50 litres compared to the 2x4 bed and 90 litres to grow a single plant should be more than enough.

 

Unless anyone else has any further suggestions I think this is the plan I will move forward with. I will wait to start buying things until next week just in case anyone has any further ideas or suggestions.

 

Thanks for all the contributions everyone, I aim to have this up and running in the next few weeks so I will keep everyone updated on how it is going.

[NormanNugget]

All the best with it bud, looking forward to seeing it come together.

 

Just gonna leave this here for your SIP adventures