One year update on system.
Nearly one thousand gallons of water, 200-300 new fish, and 50 square feet of canopy space later, I wish to re-count my efforts thus far and provide a solid update for the benefit of this thread and others who may wander through and not want to sift through all the pages. Pictures will come this Spring after I clean up the “greenshop” from a very dormant winter.
Disclaimer: I am not a record keeper of any kind and guesstimate most of the time offering subjective analysis only such as “the proof is in the pudding” so; readers beware!
Gravity Fed Venturi Drain to Grow Beds and Sump Recapture design ANALYSIS:
This is my best and proudest accomplishment with this system, which is why I mention it first off. In fact I will never deviate from this design after having been through multiple pump systems and float switch operations and inadequate sumps. One pump cycled the entire system and I am sure this helped cut down on costs. Not once did I ever sustain flooding unless I forgot to turn off the water valve when topping off the system during small water changes or evaporation refill. For the most part I left the system duties to one (pricey but incredibly adjustable) analog timer which required few adjustments and hardly any attention once set. In fact, if it weren’t for the simple problem that I had too little growbed space (more on that below) to use up all that water, I would have left the timer on indefinitely the entire year confident in design of the system. As it turns out, my chosen plants didn’t need that much water and I had insufficient grow bed space to cycle all that water, so I actually shut the system down completely sometimes and just left a small Dankoff Solar pump cycling within the fish tank for aeration (which proved unnecessary in the end and the solar pump was for the most part pointless). The chosen main pump, a Craftsman .33 horsepower was perfect for cycling duty and, if anything filled the main tank so adequately that I could have taken the venture drain in the main tank down a few inches to allow more water to move through grow beds had there been more of them. However, it would be easier and less complicated just to add more grow beds with a second Craftsman pump next to the other and cycle after the first pump shut down and water level in the main tank subsided (this would ensure the main tank was always being cycled and subsequently aerated and improved with fresher water) returned to normal. As it turned out, I could have watered at least twice as much grow bed volume (more later).
Tilapia
Despite my best efforts to inhibit breeding and slowly kill the original six acquired from the pet store, these fish not only survived unthinkable DO levels, non-tropical (or even sub-tropical) temperatures, multiple transfers from tank to tank, endless manhandling, my kids scaring the crap out of them all the time, overfeeding, under feeding (starvation), dropping them on the floor trying to figure out sex, etc. etc., BUT they produced an estimated 1,000 offspring behind my back (finding fry at one point living in the growbeds! And a natural pest control solution by the way)! There was never enough space to keep all the fry I wanted, but I managed to grow about 30 of these into adults while developing a more breeder friendly environment (more tanks/more water) which produced another 200-300 fry under my careful watch. Fish mortality was never an issue and the only reason fry died in the early days was due to my not realizing they were born and letting them get eaten or cycled through the system unawares. I NEVER monitored water parameters! EVER!. If it started to smell fishy I made sure the system cycled more often and that always took care of it (to the sacrifice of over watering the plants but that is where my system design was weakest). I did eat 30 adults (sorry Vegans) once the original brood stock was segregated. In the end I would say very tasty, but they didn’t achieve great sizes enough to make it worth the effort of filleting and de-boning. With limited grow bed space I was unable to cycle water as often as needed for optimum fish growth and therefore was limited ultimately by the size of my system rather than the potential of the Tilapia.
Grow Beds / Drains / and Plants
This was the Achilles heal in the system only because I failed to allot more space dedicated for grow beds within my Greenshop. Given the stocking density the system was capable of (given the fact that Tilapia are prolific and impossible to kill) I could have gotten away with two, three, or even four times the grow bed coverage I ended up with. With 1,000 gallons of water filled with 500 fish, I could have started an auxiliary greenhouse full of plants. In setting up the grow beds I got rather inpatient with developing a proper drain (the now infamous auto-siphon) and didn’t calculate the weight of the gravel when selecting the thickness of the plastic troughs (grow beds). They came on steel frames that I supported with a rail system scaffold frame, but the trough sagged between the spars when loaded with gravel (and later water). This in turn stressed the drains and they forever dripped, to the point where the catch buckets had to be emptied daily. Had I simply inserted a plywood length between the trough between spars, it wouldn’t have sagged and I’d be farther ahead on growbed design. As it turned out, I was not motivated to empty the gravel and start over. I left it the entire year. I thought I had a good drain system with a dam like mound at the end of the grow bed that was built up higher than the water level and forced water through the gravel rather than over it. This also allowed the incoming water to fill faster than the outgoing water and in the end was good enough to allow flood and drain. Better yet, I ended up digging out a center channel (much like a river bed) and with use of the solar pump on continuous flow in the summer I could keep about two inches of water in the growbed at all times (lower than the root systems of the plants, but high enough to keep a little creek going down the middle. This is when I noticed Tilapia fry in my little creeks. Within two weeks, the lettuce leaves stopped showing holes in them and the growing Tilapia fry would hang out under the leaves and I assume prey on insects. I never fed them. This worked very well until I started to worry that the pump would fail and the creek run dry, stranding the fry. I managed to filter about 30 fingerlings out of the creek bed and into the sump tank, but the lettuce never had problems after that for about a four month stretch. I grew Lettuce, Basil, and Cilantro, all very robust and tasty. Everything has become overgrown and the lettuce plants have since flowered and gone native! Initially I just threw the seeds into the gravel and they remained dormant until I tore the roof off the Greenshop and replaced it with polycarbonate. Everything sprouted and it has never been the same. The gravel medium I chose was satisfactory and not too fine. In fact I enjoyed making creekbeds out of it and observing the miniature ecosystem. The water would flow in at one end of the grow beds, run it’s course down the middle like a flash flood filling a dry wash and solids naturally came to rest in little eddies and pockets of gravel while plants grew wild on the riverbanks….
Analysis and Future Plans
Me and the Missus were going to get a small piece of land so I could get the greenhouse I needed to accommodate the grow space needed for this system and more. However things have settled down and I am searching for ways to expand my space within the parameters of our .38 acre plot in the city. At the very least I will be able to double growbed space inside the Greenshop by moving the sump tank underneath the growbeds and building a wider frame platform to add two more troughs. Although I fiddled with the auto siphon, I didn’t follow through once the winter started coming, so come Spring it’s me, plastic pipe, a cold beer, and Les on the horn! I am convinced auto siphons are the solution to growbed drainage, although I will miss seeing Tilapia swimming in my growbeds. Solar anything is difficult in the winter here and after this winter, convinced that it needs more attention. Fish simply do not grow when water is cold, particularly Tilapia. More insulation is needed. I still want to grow rice, but it will have to wait until I can spare one growbed without sacrificing the water quality. This year it will be drains, more beds, and increasing insulation and thermal/passive solar retention.
Auxiliary greenhouse and rice…..2008.
Backyard Aquaponics
