Updated Layout, Electrical Draft

So here it is, an updated layout with an IBC for better representation, and the latest incarnation of the GB+DWC setup.  The reconfiguration of the grow structure has allowed me to regain some space closest to the patio doors.  The electrical run is shown in pink.  There should be about 15" between the grow structure and the step that leads up into the patio door, meaning there is more than 15" between the structure and door itself.

The area on the floor in green is more than 2 feet away from any wall or barrier.  The yellow areas are within the 2' range.  Thus, I can move the grow structure even further away from the door, though not terribly much more.

I have yet to spec the actual components for the electrical.  Right now I need a minimum 3 outlets, all GFCI-protected.  I am thinking of putting a main cutoff on the left, on the pipe run originating outlet box (the grey box lowest to the ground to the left of the door).  The outlets will need to be wet-location protected.  I would also like to integrate a timer into the build, for the lighting.  I have one which isn't being used - it used to run the pool pump (but the pool is gone...for now).  It would fit nicely in on the left or right.

I'll also have to see how much wire each of the electrical appliances comes with.  The water pump should be no problem, I think it came with a ton because it's submersible.  The air pump, on the other hand, may be another story.  That said, I will need to experiment with the length of the air hose to see how it affects pump efficiency.  If it's not terrible, I might be able to store the pump close to the outlets and run longer air lines.  One way or another, I'll have to come up with a way to protect the air pump from the elements.

I am currently in the process of researching LED lighting options.  It looks like a DIY build will be required, if I want any reasonable amount of light output.  That said, I'm not sure how much light I need.  There's only indirect light back there, so some direct LED is a minimum requirement.  Having it be DIY also means I'll need to properly store and protect the LED drivers and any power transformer equipment...gaaah!  IP66 anyone?  Perhaps rated fixtures are not such a bad investment after all...especially if I could find some on eBay.  Or perhaps I should build or attach a weatherproof box to the back of the grow bed?

If you're wondering why no HID or fluorescent, I simply don't have the headroom for the lower tank, and really not for the upper tank either.  I'm not even sure how I'm going to mount the LEDs for either.  But an LED bar should be no thicker than a T5, when it's completed and mounted, and should put out significantly less heat.  Moreover, and the main reason, it should cost significantly less in power.  That's a big deal.  That, coupled with low voltage (always a nicety around water) and the potential ability to encase a good portion of the electronics in epoxy (waterproof!!), makes LEDs very attractive.

Modeled, but not shown in the picture above, is the sloping porch ceiling.  The long horizontal electrical pipe running over the patio door is situated just below where the ceiling meets the wall.  That's also the highest point for the ceiling, so perhaps you can appreciate the headroom situation.

Grow Structure Design Update

On and off over the last couple of months, I have been toying around with different ways to support the grow bed and DWC/sump.

Various ways to put the GB on top of the DWC.

 There are two key problems I have to solve:

1. The bottom of the grow bed must provide sufficient clearance to allow both functional DWC access, and to ensure the DWC lighting will not be too close to the plants.
2. The patio where the system is to be located has a very unfortunate slope: approximately a 1 5/16 inch drop over an 8 feet run.

Point number 2 provides a most amusing problem.  The DWC tank is 8 feet long.  Left unchecked, one side of the DWC tank (and, of course, the GB) will be 1 5/16" lower than the other.  Since the pump will be located on the high-side of the tank, this is no bueno.  I have toyed with some options for dealing with the slope.  The first, and so far still the best, is to cut several ramps that will act as combination joists-and-slope-correction.  Another alternative was a set of wedges, cut so as to be placed at regular intervals along the bottom of the DWC tank.

Mounting the GB above the DWC is also an interesting challenge.  As I mentioned above, the DWC needs to remain accessible.  I figure I should keep a minimum 12" between the top of the DWC and the bottom of the GB supports to ensure good access (meaning I can get my boards in and out, with large plants, without crushing or destroying anything living in the process).  To complicate things, I also cannot have the GB situated too high, or it will become difficult to plumb it and to access it during actual operation.  Due to the slope problem, the DWC tank will also be situated slightly off the floor, thereby reducing the already limited clearance between the DWC and the GB supports.

Another goal is ease of build: I don't want to mortise if I don't have to, as it's a PITA.  Considering the weights involved, I also don't want anything potentially compromising the precision of the legs.  My calculations put the DWC tank weight around 1,000 lbs when filled.  The GB will probably be in that ballpark, as well.  Much of the GB's weight will depend on the weight of the media.  I'm planning on going with Aquarocks: a sort-of Hydroton alternative, where if Hydroton and lava rocks got together, Aquarocks would be their baby.

As if this all wasn't enough, the patio slope presents a bonus problem: the legs of the GB stand will be tilting by approximately 0.8 degrees.  Over the 3.5" width of the leg, this equates to one side being a little more than 1/32" higher than the other.  If the legs are 30" long, the top will be displaced by roughly 0.41".  Lateral force due to the 1,000 lbs load should come to something like 13 lbs, so it will be as though there is someone pushing against the legs with 13 lbs of force at all time.  Now that I have that written thus, I may be reconsidering my plan to not slant the feet of the legs.  My only hope - and perhaps I should check a physics book on this - is that the load will at least be distributed among 6 legs, so 2 lbs lateral force per leg.  Also, given that there will be 998 lbs of downward force, perhaps this is really all moot.

Here's the current draft plan, plus a look at how the tote squeezes in on the patio:

The build: notice the purple slants.
They're there for a reason.

Large, beastly recycled IBC tote, located where it needs to go.

The one problem with the tote is that it forces the "near-end" of the GB/DWC out away from the wall, breaking the clean lines that had always dominated the system.  But that's fine.  A small sacrifice for an extra 130 gallons of capacity.

Build Update 2016-APR-23

Today we purchased a recycled IBC.  This will become the fish tank in the now-modified build.  More modifications to come.  The tote itself was available with a new bottle.  It was slightly more expensive, but since it has never been used we can be assured there should be no contaminates lingering.  I'll wash it out all the same.

The tote is a 330 gallon, which is about 130 gallons larger than the tank I had originally spec'd.  I'll have to use a SLO to deal with the waste accumulation on the bottom, but I'm hoping that will work OK.  An alternative would be to use the bottom drain itself, but I hesitate to do that, partly because it's facing the wrong direction.  The tote is also shorter than the cone-bottom tank, and since it's free-standing it was also about 1/4 the cost (i.e. no stand required).  I may place it on some PT 2x4's just to get it off the ground, since the back porch gets quite a bit of rain-water on the floor.  It's really just an accumulation, but also quite an annoyance.

I built the two frames (below) a few months ago.  Unfortunately, the project has stagnated due to lack of funds.  On the bright side, this has given me time to reconsider the fish tank (which is why it's now a tote), and time for the PT lumber to dry out.  With it dry, it will be easier to paint.  I still have to purchase and cut the PT plywood, and have been reworking the grow bed stand.  I am hoping to fix a few design concerns I had, and make it so that both the upper bed and lower DWC tank can be properly leveled.

The lumber, all cut and labeled

More pre-cut pieces.

The two boxes, sans bottoms.