Project Update: Electrical Install

Before I lose access to parts of the porch, I have started running the electrical.  A snapped concrete drill bit today stopped my work before I could complete the first run, unfortunately.  Still, I managed to get quite a bit done.

The nearest receptacle is quite a bit away from the grow beds.  I have opted to run schedule 40 PVC electrical conduit from just above the existing receptacle, overhead of the porch door, and down to the right of the door (in the space between the door and the porch screen wall).  The conduit enters a 2-gang weatherproof box, where power will be delivered to a GFCI outlet.  From that outlet, power to the other outlets and the timer (for the lighting) will be drawn.  This means that everything downstream from the GFCI outlet will be ground-fault protected.

I had initially planned to use an existing single-gang electronic timer to drive the lights.  Upon further consideration and research, I decided that it would be better to use a standalone hardwire timer, one rated to significantly more wattage than the single-gang would have provided me.  I chose this one:  http://www.intermatic.com/en/products/timeswitches/electroniccontrols/24hour_7day/gm40ave.  I haven't had a chance to test it, since it's only installed and not wired.  The way I have it mounted, I can either run the return power back to the 2-gang box and manage an outlet there, or run a separate conduit down from the timer to a dedicated LED driver box.  I will most likely be pursuing the latter.

While I am trying to do everything to the NEC code (and I have the large, blue 2008 version sitting in my living room), I elected to leave the bottom plugs of the 2-gang box unsealed.  This was a wise decision, since I realized before this evening's run to our local home improvement store that the pump plug wire was not going to reach to the 2-gang outlet box.  I'll be running another conduit and placing an outlet right behind the IBC tank.

Please note that everything is being weatherproofed, so any stray sprays of water, splashes, or even a good soaking, should not cause any damage or death.  And, of course, the GFCI is there to help with that.  Everything, from the conduit to the wiring to the enclosures, is rated for wet locations, as defined in the Code.

As for the lighting, I have started doing more research on that again.  We recently purchased some LED flashlights.  The beams are adjustable, and with the focuser pushed all the way in you can see the actual LED element.  It's a single-lens array, square in shape, and the output is 350 lumens.  It is quite bright, and has caused me to reconsider just how much light my system actually needs.  I am thinking that it may be time to do some basic testing.  I have begun pricing out some components, and may make some purchases soon so as to get some experiments done.  What I would really like to do is set up a few makeshift grow chambers out of opaque plastic boxes (think the giant tubs for storing your junk in).  With these, I could set up three or four experimental lights and test a small tray of seedlings in each.  My control would need to be a similar tray positioned outdoors, for direct sun.  Unfortunately, I'm not sure I have either the time or the money to do this.  But then again, considering the thought of wasting money on the wrong lighting...

Bulkhead Fittings and Siphons

I have purchased a small selection of bulkhead fittings from US Plastics, an online supplier of those and evidently a large variety of other plastic-related items.  I am currently gearing up to procure another round of supplies, at which point I will be very close to the point of being able to fill the system with water.

Since I had to purchase fittings, it seemed like a good time to do some calculations and make sure I was sizing the plumbing appropriately.  I assume a pump rate of 800 gph (it's a 1000 gph pump, but I am attempting to account for head loss).  I can't seem to find the calculations (they must be in another spreadsheet), but for the moment I am assuming that the media will occupy about 30% of the GB space.  The GB's max operational capacity is approximately 100 gallons.  Thus, we will suppose 70 gallons will filter into the GB before the siphons start.

Given the above, the anticipated static fill time (the time it takes to fill completely before draining starts) should be about 315 seconds.  A 1 inch diameter drain pipe should pull the water out of the GB in about 200 seconds.  Figure in the constant fill rate, and the drain time jumps to 547 seconds (we'll call this the dynamic drain time), meaning it would take far longer to drain than to fill.  At 1.5 inches of drain diameter, we should expect 124 seconds of dynamic drain time.  That's better.  At 2 inches, it should drain all 70 gallons in about 59 seconds.

Now, I can only cut these holes once, and I am slightly concerned that the length of the bed will cause one side to become more stagnant than the other, should I place the drain in one corner.  The alternative is therefore to add a second drain.  Two 1.5" diameter drains equals one 2.12" diameter drain in drain area, so the dynamic drain time would be around 52 seconds.  Two 2" drains (equivalent to one 2.83" diameter drain) will reduce the drain time to 27 seconds.  These times do assume sufficient out-piping, which means I would probably need to enlarge at least a portion of the pipe running down to the DWC.

Whether or not I really need the second drain is up for debate, but by at least installing the bulkhead fitting now, I can always add the actual drain later (and otherwise just plug the hole if it need not be used.  If I do go with the larger size pipe, or two of them for that matter, I will very likely need to contend with a siphon start issue.  Thinking back to the pull-start siphon I experimented with several months ago, I decided it might be good to find a way to build that in.  Putting two bulkheads next to each other, however, did not seem like a good idea, and the loss of GB real-estate was becoming bothersome.

One potential solution, which I will be experimenting with as soon as the fittings arrive, is to put the start-pipe assembly above the bulkhead, rather than below it.  In concept, there would be only a single pipe and single bulkhead fitting.  The pipe would tee immediately above the fitting, and proceed up at full diameter and out at the start-pipe diameter (1/2" most likely).  The start pipe connection would do a bend and then run parallel to the main drain, terminating just below the top of the main.  The start pipe would therefore set the max water height in the GB.

Two siphons should not pose any special difficulty, as long as they are drained together.  If the main (pull-started) siphon is closest to the out-pipe, and the secondary siphon connects into it just before the out-pipe, the secondary siphon should get pull-started by the main siphon.  That is, once the main siphon trips, it should pull sufficient vacuum on the drain plumbing to forced the second siphon to start.  The effect will be a three-stage drain: start, primary, secondary.

It may be better to put the primary siphon upstream of the secondary, but my only concern is that the long horizontal run will cause problems for primary siphon start.

Regardless of how the siphons are started or how fast they flow, this action has an effect on the DWC tank:  given the dimensions of the DWC, a 70 gallon ebb-and-flow will equate to approximately 5.6" of rise and fall.  Consequently, the pump will need to gather water from as close to bottom as possible.  It should be noted that this height changes is slightly more than 50% of the maximum water height for the DWC.  Should it be determined that less water is required in the GB to trip the siphon, then this percentage will be reduced accordingly.  (For instance, a 50 gallon ebb-and-flow will equate to a 4" rise and fall.)

I plan to position the water pump outside the DWC, piped so that its inlet it always submerged.  I may need to find a decent filter material to keep debris from entering the pump.  One of the bulkhead fittings I acquired is intended to go through the wall of the DWC.  This is mainly to ensure that the pump can be properly primed before starting, as it is not self-priming.

Testing will hopefully commence soon!

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 Revision - Media plus DWC

I purchased a copy of the Green Acres Aquaponics' manual, which describes both the basic knowledge required for aquaponics and their specific build projects.  It was a good read.  I skipped a good deal of the basics, having already obtained them from multiple other sources.  But their build was fascinating.  They basically have a compact system that sports a small-ish fish tank (100 gallon I think), a roughly 4-ft by 4-ft media bed, and a 4-ft by 8-ft sump and DWC tank.  You can get all 8 feet of sump to work as DWC if you have the floor space available.

This turned me on to something I had been mulling over since I first designed my prototype: how to make use of that blasted sump.  One idea was to add media to it, to improve the bio-filter.  But without growing plants, it seemed like a bit of a waste.  The GAA manual also demonstrated how to use a specific liner for their builds, and that opened the door to this:

This is a media bed over a combination sump/DWC tank.  The upper bed is 2' by 8'.  The lower is 3' by 9'.  Since the entire system has to fit in a very small footprint on my back porch, and will already require artificial lighting, I'm planning on simply adding additional lighting to the underside of the media bed.   The last foot or so of the DWC will either get lighting somehow affixed over it, or be partitioned off and used as a place to add chems, etc.  While most publications seem to favor putting the pump in the sump tank, I still think I'd prefer it to be outside the tank for ease of access.  Guess we'll see how everything fits on the porch.

The GAA build also sported a radial flow clarifier.  The clarifier fed directly into the sump, and the media bed drained into the sump via bell-siphon.  I had originally started planning one into this build, but then changed my mind after figuring the media bed would probably provide sufficient filtration of the particulate matter.  That said, I can always add a clarifier later.  My idea for the clarifier was to set it high enough that I could set the sludge drain to empty into the media bed.  After all, the media bed was going to get straight fish water one way or another.  Theoretically, managing the plumbing such that the outlet for the clean water and the outlet for the sludge would be at the same elevation ought to give me two outlets with two different purposes, from the same device.  This will be something worth experimenting with in the future.

I have yet to price out the lumber for the above build, and the build requires a little further fine-tuning anyway.  If the total price comes out below the original build, I think that'll be a great value.  If higher, it will probably still be worth it for the fact that we'll more than double our growing capacity (since DWC gives you a much higher plant density than what you can achieve with media).  If significantly more - which I'd have a hard time believing - then we'll reassess just how important the DWC tank is.

Some things that this build doesn't give me: I won't be able to control the media bed flood and drain rates as much as if they were two separate beds - this means less opportunity for experimentation.  The DWC might suffer from particulate accumulation without the clarifier; we'll see.  The top of the media bed is quite a bit higher than the original plan called for - or at least I think it is...I haven't measured yet, but it's at around 40" at present and I don't want it to go much higher.

I'd love to have the space to spread things out, rather than planning to bend and stoop for DWC plant access.  However, this is a trial build after all and hopefully, with sufficient lighting, we'll get a good return.

My Trial System Design and Project Plan

Very soon after I had devoured the book Aquaponic Gardening: A Step-By-Step Guide to Raising Vegetables and Fish Together, by Sylvia Bernstein (ISBN # 978-0865717015), I set out to draft my first system.  Here's a peek:

The trial system configuration

Goals

My goals for this system:

• Keep it small, but large enough so that we can stabilize the system and keep it running for at least one whole season.
• Minimal investment in structure - let's not build a huge greenhouse before we know we can actually make this work.
• Use a nutrient solution transport scheme that has had high reported success and minimal impact on the fish.
• Make the framing components extremely easy and cheap to build (the picture above is not accurate to the final specs)
• Large plumbing for minimal cleaning.
• Keep the pump accessible.
• Design for maintenance.
• Design to mitigate failures and fish-death.
• Design for future expansion.

System Design - Overview

To achieve these goals, I have set out to do the following:

Plumbing View - Grow bed assembly removed for clarity

• The system is a 200 gallon cone-bottom fish tank, a 100 gallon sump, and two 50 gallon grow-beds.  This technically gives me a 1:2 ratio of fish tank to grow-bed space, where the preferred ratio is 1:1 or 2:1.  I can compensate by simply not adding as many fish.
• By putting this on my back porch, I have an enclosed space that I can manage and is convenient for monitoring and upkeep.  No structure builds required.  The downside is that I need to supply auxiliary lighting, which means either buying or building lights.
• I toyed around with CHOP-1 and CHOP-2, and finally settled on CHOP-1.  While I'm not convinced of the problems that detractors of CHOP-2 go on about, CHOP-1 plumbing is easier by far.
• The framing components for the grow-beds will be made of 2x4 lumber.  All the cuts are straight (again, ignore the portions of the picture where this does not appear to be the case, that was an early draft).  Assembly can take place with screws and carriage bolts, the latter for the most significant load-bearing members to add rigidity and strength.
• I will have to double-check the size of the NPT fitting on the bottom of the fish tank, but I believe it's 2".  I plan to run the largest diameter reasonable from the fish tank to the grow-beds, to ensure good flow and minimal clogging.
• All the plumbing should be sufficiently accessible.  Space is a bit cramped, but I have positioned the system components such that nothing is completely inaccessible.
• All plumbing will be valve-governed.  The under-tank plumbing will probably be glued wherever slip fittings are used.  This is to mitigate a pressure disaster.  Not visible in the picture above is a valved outlet, which could be used to drain the majority of the system if things go very wrong.  The valves will allow me to disassemble whatever portions of the system I like - within reason - without having to move the fish and drain the fish tank.  Where pressure should not be a significant issue, I will probably use unglued slip joints, as is the common tendency (this allows easy cleaning of the smaller pipes, as they can be disassembled).
• I have tried to design the plumbing such that if there is a pump failure, the entire tank doesn't drain to the sump.  The system is configured such that the water in the fish tank must rise sufficiently to spill over into the grow bed flood plumbing.  The spillover tube is open at the top (the blue vertical tube in the illustration above), so that no siphon can form.
• Finally, with the size of the tank, grow beds and plumbing, it should be very easy to expand this system by adding upwards of 6 more grow beds, without changing out the tank.  Additional sump will be required, if/when we get there.

Related Topics and Research

In doing my extended research, I investigated the keeping of koi.  These fish have rather particular water clarity needs, and so I felt they would make a good study in just how clean one could keep a pond or tank, and in what methods would serve to best achieve this.  Some of the interesting tidbits I collected from the koi pond building guides were:

• Large plumbing is essential.  Under-sizing leads to clogging, mainly due to the typically low flow rates.
• In koi ponds, once practice is to feed into swirl filters first, then get to media filters - if you're interested in removing the maximum amount of contaminants and not growing plants with them, that is.  Multiple swirl filters can be attached in series.
• Bottom drains work best, as they encourage the capture of just about everything that falls to the bottom (thus my choice in a cone-bottom tank).  These are usually built into the koi ponds during construction.
• Pipe purging can be done by creating a fast water flow.  In some koi ponds, this is done by disabling the filter feed pipe, draining the swirl filter, then enabling the filter feed pipe.  This (theoretically) allows water to flood in rapidly, dragging accumulated contaminates through the pipe and into the filter.  I should be able to do the same with my valve system.
• Ideally, the pump should be places after the filtration assembly.  This improves pump life and reduces clogging at the pump.
• Any inline heaters, UV lights, anaerobic filtration equipment, water polishing, and such, tend to go after the filters, and either before or after the pump.

While some of these points will not be highly applicable to aquaponics, I think some practices may prove beneficial.  In a future iteration I would like to employ some swirl filters to clean the water in prep for delivery to a NFT or DWC array.

Lighting

One of the unfortunate side-effects of using the porch is the lack of direct sunlight.  There is plenty of diffuse lighting, but I do not believe that will be sufficient for even my trial plants.  I have been investigating various lighting options.  Here's what I've considered:

• HIDs - low entry cost but high energy usage and possibly short lifespan of bulbs.  
• Metal Halide - bluish light that is good for vigorous plant growth.
• High Pressure Sodium - reddish light that is good for fruiting.
• It is ideal to use both kinds for the different stages of plant growth, but this requires a ballast that can energize both kinds of bulbs (or more than one ballast).
• T5 fluorescents - moderate investment, lower energy usage than HIDs.  
• Bulbs reportedly need to be replaced after 6 months.
• LED - higher initial cost, lowest energy usage.
• Research is comparatively scanty on LEDs for plants, but there is a growing industry and community.
• DIY LED lights are possible.

My ideal lighting solution will probably be LED, and by that I plan to manufacture my own grow-lights.  There are several how-tos and at least one excellently engineered build-guide.  WHen compared to the buy-and-install of HIDs and fluorescents, LED lighting construction is not trivial.

• Power Supply
• An LED driver is required.  You can get LED drivers and drive them with D/C power, or purchase an all-in-one driver unit.
• LED Assembly
• Some people use red/blue diodes, others use white.  
• Power LED lights require heat dissipation measures - a heat-sink or metal backing plate.
• Cooling
• Passive cooling is obvious and easy.
• Active cooling requires power; the LED power source might provide for this, otherwise separate power requirements must be met.

Aeration

To assist with aeration, I plan on eventually having two systems in place:

• Venturi aerator - this will be driven off the return water feed, so pump-powered and run directly back into the fish tank.
• Air-stone pump - ideally with a backup power supply, this could run air in both the fish tank and the sump.

There are several online examples of DIY venturi aerators.  The construction is extremely simple, so I will be experimenting with that as well.

Project Road Map

I will be performing the testing and evaluation step first.  All other steps will occur as time and materials become available, so the order of events will not necessarily be as listed.

• Build, test, and evaluate critical system components:
• Siphon construction
• Venturi aerator construction
• LED lighting
• Install the electrical
• Build the grow-bed support frame
• Acquire:
• Fish tank
• Grow beds
• Sump
• Miscellaneous system components
• Plumb the system
• Build the full lighting fixtures
• Grow Bed assemblies
• Build, install, and test the siphons
• Evaluate fill/drain times against estimates
• Cycle the system
• Acquire fish
• Add plants
• Grow!