Backyard Aquaponics
A place to discuss aquaponics

I've signed the lease for my greenhouse!
Now the real work begins...

I'll upload a google sketchup soon, but here's a sloppy preview:

Congratulations....

No rest now for you then..

Oh yeah, csant wait to see more!

First water readings, straight from the tap:

KH - Off the API test scale. Took 14 drops to change color, scale only goes to 12. ( so 12+ *dKH)
GH - same, off the API scale. Took 13-14 drops to change color. (12+ *dGH)
pH: 8.0 (ish)
- left some water to bubble over night, but given the hardness, I don't expect it to go anywhere...

Copper - none, but just wanted to make sure.
No fish yet, so haven't tested any N values.

I knew I'd have hard water, as this is well water, but it looks like I'm in TXLynx territory!
That's fine with me, actually.

Those water readings may be F`ed up. The current renter has his fertilizer plugged into the water system. I thought I'd drawn my test water from a clean spigot, but nope!
Ordered pumps, aerators and liner. Lots of watching for the delivery truck now.

What a great space, Congrats on making the big move.
Any more ideas on what your going to grow and are you doing your own seedlings.
All the very best of luck.

My system is going to mostly be a raft system, but with growbeds at the beginning of the line to filter the solids.

IBC FT --> 100gal stock tank gravel filled growbed --> raft system --> sump

When building the raft sections, I intended to use the Friendly system: 2x4s around the rim, held up by form stakes, and protected by thin plywood. Staple the liner on the inside. They recommend using 2 ft (600mm) formstakes, 3 ft (900mm) for softer soil. Here's a pic showing the structure, on one of their test tanks:


This is the raft systems look like on a standard tank:


However, since we have such cold winters here, and despite the greenhouse, I want to make my raft system twice as deep, in order to have more water in the system and therefore more thermal stability (and maybe throw some crayfish in the bottoms of the troughs).

I also want to insulate the troughs.

The liner (12' x 100' [3.6m x 30x5m]) is incredibly strong, as the top pic shows, and doesn't need to be braced on the sides to keep it from expanding out horizontally. I figured to make the trough 2 feet (600mm) deep, I could just use longer form stakes.

I went ahead and ordered the extra-wide liner before bothering to figure out the longer form stakes, because I figured they'd be not too much more expensive than the 3' form stakes, and easy to find. Boy, did I miscalculate that!

Longer form stakes (4ft, 1200mm) are incredibly expensive, like $9 US per stick. As I need to buy roughly 200 of them, that clearly isn't an option. I might as well build the troughs out of dimensional lumber at that price.

So, a number of questions:

1) Because my troughs are twice as deep, should I upgrade the upper rim from a 2x4 to a 2x6 or maybe 2x8 to take the weight of the extra foot of water?

2) Can I continue to use the 3 ft form stakes, but attach them to 2x4s that I hammer deep into the soil?
2a) If I'm using the vertical 2x4s anyway, can I just go without the form stakes?
2b) or for that matter, like in the first picture above, use 2x4s above the soil, and hammer the 3' of form stake down into the soil? Maybe a foot of overlap to attach the stake to the 2x4?

I'm going to attach foam insulation below the rim 2x4 along the sides, and then put thin plywood on the outside to protect it from rogue toes and wheels.

I was going to just line up foam insulation along the bottoms of the troughs without any support.

3) Will the water compress the bottom foam too much, and take away the insulation properties? Do I need to build a plywood structure to protect the foam from crushing? A la the bottom of the Growing Power setups:


4) Or should I forget going 2ft deep on my troughs, revert to 1', save a ton of money, and just roll up the extra liner on the sides? (But also wasting the extra $$ I spend on the wide liners, before I priced the form stakes)

5) Or should I go whole hog and build the troughs out of dimensional lumber like Growing Power and JT's beautiful beds? (see JT's here.)

Growing power's setups. I wouldn't build the full 3 tier setup, just use this method of building on the bottom trough.


Thoughts?

Here's a screenshot of my active sketchup file on this project. You can hopefully see I'm planning on building the troughs in overlapping sections --

|=====2x4====|=========|
~~~~~~|~~~~plywood~~~~~|~~~~~~~~



I'll join the 2x4s end to end using a kreg jig, that I learned about here on this forum. Thanks, whomever that was...

Gathering supplies on the loading dock. The liner is the double-pallet in front:


The actual greenhouse space is currently occupied by a guy growing a ton of tomatoes. He should be leaving near the beginning of June, and I can move in.



I was also going to mention...
Remember, this is how the GH looks empty:

Each dirt side is a bit over 11 ft wide, and the middle cement walkway is 5 ft wide. So I was planning two trough sections on each side of the walkway, for four total per greenhouse.

Wall| 1 ft | 4 ft trough | ?? foot walkway | 4 foot trough | Cement walkway | repeat other side

With a 4' wide trough, (wider, since the water is 4' wide, and then there are the walls made of lumber and insulation) that leaves the walkway between the troughs pretty skinny. This is why I want to use form stakes instead of full-on dimensional lumber -- to save space for walkways and carts.

JTs design would be a lot easier to insulate and with that design you should be able to maintain your 2 feet deep. IMHO.

IMHO plywood is very expensive (something like $25 per sheet at Lowe's?). I'd minimize the use of all materials involved, maybe you can find a lot of savings from optimizing it further. The only essential material is the liner, right? It's be a shame to spend 30% of your material costs on 4' rebar stakes or something like that...

I wouldnt chose the "Frienly" system. Just doesnt look strong enough. I have seen some liner swimmingpools to crack, and flood the garden in a second. Those form stakes are designed to hold concrete framework temporarly. These together doesnt look promissing to me.

I would choose the Growing powers design, that looks like one that will stay like that till eternity. But be carefull, if you dont build the 2nd and 3rd tier your cross section will look like a big U and will fold out. You need to connect the stands not only on the bottom but on the top as well. This way the cross section will look like a sqare and wont fold out.

But whatever you choose compact soil well before starting the layout!

- Depends on the insulation type you use! May be the high density EPS van handle that preasure, if not look for extruded expanded polystyrene (XPS) thats water proof, and can handle 3 tonns/sqr meter.

Skipd; yeah, I know it'd be much easier to insulate the fully-built troughs. It would also double or triple the cost of the troughs to build them in a JT/Growing Power style. I can insulate them just fine with the 2x4 rim troughs, just using a different method.

zsazsa; You've given me really good info, and I'm very grateful, and I don't want this to sound anything but grateful but the Friendly system IS strong enough, at the depth they've built their troughs. They've been running those for a few years now, and Tim happily sits on the edges of his troughs with no problem. This isn't standard pond liner, this is DuraSkrim, a re-enforced film. (I took the Friendly training last spring, and even after reading about AP and doing it myself on a hobby scale for a few years, I learned a ton from their training).

My question is: given that I want to make mine deeper, is the Friendly design extendable to deeper troughs? I guess I'm just going to have to build some test troughs and see.

Another thing to think about is that this is only a temporary location. I hope to only be here for a few years. If I use the Friendly system, I can empty the troughs, undo some screws, and load up the system onto a truck. If I build the full-on Growing Power systems, those are not in any way portable, and would have to be completely deconstructed to move them to their permanent home in a few years.

If this were the permanent site, I wouldn't be thinking about using the Friendly troughs. But keeping costs down at this point is absolutely critical.

How do you calculate (or rather, do you know the formula) for calculating the weight of the water in the trough? I mean, I know water weighs roughly 8 pounds / gallon, but I don't know over what distance materials are rated for. *sigh* I wish my engineering background were stronger (read, existed at all)...

To quote Faye:




Don't skimp on materials. Build it as strong as you can so you won't need to repair it, modify it or start over again.

Ok! Now I understand your reasons. In this case I would choose 2a!

The strength of the stake(pile) depends on the consistence of the soil and the surface of contact (the bottom and the sides as well) between pile and soil.

Hammering down 2x4 wooden piles gives you mutch more stength than those small formstakes. Because of the surface it will be mutch harder to hammer down. You need strong wood with pointed to be able to hammer it down. You might need an iron cap (or ring) on the top of pile because it can easily crack while a hammering.

Wood in soil naturaly weakens by time, i would get some treated ones that resist more against water, bugs, worms, etc.



Some weight of water will be held by the sides(stakes) but most will be on the ground over the insulation. You can calculate how mutch the sides hold but if you just ignore it and calculate with the whole weight you do nothing wrong.

Weight of the water: (I'll go metric sorry;))
We need to find out how mutch water will be over 1 sqr meter, to know how many kgs/m2 preasure we have to deal with.

1 liter of water = 1 kg
1 liter of water = 0,001 m3 size
0,001 m3 water = 1kg
water weights 1000kg/m3

You have 60cms of water over an area of 1 m2. We deat with the weight of a water cube measasures 0,6m x 1m x 1 m x 1000kg/m3 = 600 kg

The preasure will be 600kgs over 1m2 >> 600kg/1m2 = 600kg/m2

Regardless of the depth of the bed, the greatest pressure will always be at the bottom of the bed/water column. This is why when they rotomold large plastic tanks (10,000 litres plus), the thickest area is at the bottom wall area of the tank.

This means were you to run 2' deep GBs I would suggest that a 2x4 (maybe a 2x6)at the bottom with a 2x4 at the top as usual with the friendlies system. Then increase the number of stakes thereby decreasing the distance between pressure points. You may still get bulges and ultimately failures in the ply immediately above the new bottom plate depending of the thickness of the ply. Going up one ply will probably solve this, but add to the costs.