Ecolibrium Aquaponics

Our foray into the world of hydroponics, or, in our case, Aquaponics, has netted a wealth of new knowledge and a heaping helping of hindsight.  The concept is great, a closed-loop system that sustains itself.  Feed the fish, the fish feed the plants and the plants clean the water for the fish.  Our system was successful in the realm of keeping the fish fed and healthy.  We noted a marked level of growth in all six goldfish, wonderful news if we had been building an aquaculture system and not an aquaponic system.

After we solved the pump control problem, the Arduino controller worked flawlessly while performing continuous duty.  Weekly, I stayed long enough to observe at least one flood and drain cycle to ensure that the surge pump was working and that there was no malfunction in the bell siphon.  Unfortunately the low cost aquarium pumps proved to be just that.  The number 1 pump began to exhibit signs of bearing failure about two weeks ago.  The howling indicates that the annular ball bearings are failing.  We decided to leave it alone.  Had it failed, we would have subbed in the number 2 pump by switching the wires at the relay card.  Pump 1 obviously was not up to the task of extended, continuous duty.  Pump 2 has shown no signs of failure or premature wear.

We tried twice to plant lettuce seeds but they never took.  While digging through the grow media, we did find one tiny seed with two little leaves. Our assumption, as with the radishes is that the hydroton doesn’t provide enough support or protection for the fragile seeds. In retrospect, we should have bedded or germinated seeds in Rockwool cubes and then placed the cubes in the hydro clay bed.

Throughout the growing process it seems as though the fish waste (nutrients) did not disperse throughout the grow bed as we had planned.  The healthiest plant was always closest to the trickle of water feeding the grow bed.  The indication here is that the nutrients were deposited right below it and were not migrating throughout the bed during the flood cycle.  I attribute this mainly to the fact that we had to reduce the pump flow rate to a trickle that did not exceed ten fluid ounces per minute.  Had we been able to run the pump un restricted, we surmise that the fish waste would have been delivered to the grow bed instead of settling out in the pump line.

 

Unfortunately our plant is holding at four small leaves.  It has not died but it certainly is not growing.  At this point harvest is in one week and there is no realistic chance of having a harvest ready plant by then.  We can now reflect back and discuss what we would change in version 2.0, but we believe it is time to accept that this system was a bust.  (Joe Steinmacher)

 

Today we found that another plant had brown leaves and was essentially dead.  We pulled that one and now have one plant left.  Interestingly enough, we pulled out the healthy plant to look at the root structure and found that it only had one long white root.  The white root suggests that it is living and healthy.  However, the fact that it is only one makes us thing that the plant still has not taken to the medium correctly.  The clay balls may be too loose of a setting for plants that young, and therefore do not give it the support we want.  This could explain the lack of growth we have seen.  We will have to brainstorm a solution to the problem and try to implement it.  Unfortunately, time is running out! (Joe Steinmacher)

In an effort to keep the last living plant “rooted” we installed a support ring in the hydroton, hoping that it would keep the media from shifting during the flood cycle.  The last plant is alive but it doesn’t look particularly healthy.  We also believe that the fish waste, the plant’s source of nutrition is not being dispersed through the grow bed well enough to support proper growth.

 

Today I went into class to increase the amount of food the automatic feeder was giving the fish.  My thought is that maybe more food will equal more waste and therefore more nutrients.  Unfortunately, there is no growth from the day before. (Joe Steinmacher)

 

After the weekend, we found that there is still no more growth in our system.  The pH of the water is about 8 from day to day, which we believed to be ideal to accommodate the fish as well as the plants.  It is possible though that the high pH is causing an iron deficiency in the water and therefore inhibiting growth.  We added a small amount of pH down, but only a little so that we did not shock and kill the fish.  (Joe Steinmacher)

The attempt to transplant the two felled radish plants into a Rockwool slug has, for all practical purposes, failed.  The transplant attempt may have damaged the root and, regardless, the roots will not grow through the Rockwool.  We suspect that in order to be effective, the seed must be placed in the Rockwool soon after germination.  We took a few minutes to purge the trickle hose to try to get some of the waste out of the hose and into the grow bed.  One of the downsides of having the water pumped up about fifteen inches is that the fish waste settles out and collects in the hose.

We have noticed over time that we lose close to three gallons of water a week…all due to evaporation.  This doesn’t hurt the fish, but, two weeks without topping off the water level would effectively drain the fish tank.   Adding straight faucet water to the aquarium doesn’t seem to have much, if any stress-effect on the fish.  We do try to keep the water temperature around 70 degrees Fahrenheit when we add water to the system.

Since Monday we lost one plant.  Like before, the water pushed the radish plant out of the grow medium during the wet cycle.  Unfortunately, the plant looked dead and we decided that replanting it would not work.  To try to alleviate this problem, we placed the two remaining plants in rock wool and put that system into the clay.  We are hoping that this will allow the plants to take root and not pop out like before.  (Joe Steinmacher)

Extraction of the two downed plants proved that they had very long tap roots.  Unfortunately, the singular roots don’t have any media to effectively bite into in the hydro clay.  Settling in the grow bed has demonstrated almost an inch of depth-loss due to compaction.  During the flood cycle, the clay spheres float free; we believe this is the cause of the plants laying over.  There is some minor speculation that the worms burrowing through the media may loosen it as well.

 

 

After a long weekend, we were pleasantly greeted by a third sprout. 

Although the plants in our system are not as large as those in other systems, we are optimistic that there will be much growth soon.

We got a little bit of a later start because of the pump failure, so this is to be expected. 

Now it is a waiting game until the plants have substantial leaves. (Joe Steinmacher)

 

Growth upward has proven to be a challenge in our system.  One of our radish plants actually pushed leaves but never broke the surface of the Hydroton.  The theory here is that the hydro-clay is too loose to support the plants.  Today we also added twelve night-crawlers to the grow-bed.  They needed a few minutes to warm up and become active.  As soon as they were, they burrowed beneath the surface of the bed.  Ideally, they will further process the fish waste and help disperse it throughout the grow bed.   As a side note, the fish continue to do well and the water in the aquarium remains quite clear and “clean”.  If nothing else we’ve built a unique and effective aquarium filtration system.

 

Although it feels like forever, we finally have a radish growing.  It’s a bit disheartening because only one seed seems to have taken off.  Further investigation revealed a second radish that sprouted leaves but refuses to push through to the surface.  There is some concern that the water-logged grow bed (during the fill cycle) allows the Hydroton to float too freely and doesn’t support the plant.  We will be continuing to monitor the plants.  No lettuce seems to have taken.  We can’t find any germinated seeds in the bed.  Also, we recently added 12 Nightcrawlers to the grow bed to help process the fish waste.  Our hope is that they will better distribute the waste product so that the plants receive the nutrients they need to thrive.

 

 

Our pumping / siphoning system was a large hurdle to overcome.  Initially the relay system we were using worked quite well on the bench during testing.  When it was installed on our Aquaponics system, it failed to operate properly.  After much troubleshooting and research it was determined that the relay board we were using was triggered by an active LOW signal as opposed to the typical active-high.  After some testing, we solved the problem by changing four lines of programming that basically send the wrong polarity signal to the  relay control.  This basically turns off the circuit, causing the relay to come on.  The pump system has been operating in conjuction with the Bell-siphon for quite some time now.

Finally having solved the ebb and flow system problems, we planted 3 radish seeds and 3 lettuce seeds in the grow bed.  We used pre-germinated seeds to start and did not use anything beyond the Hydroton already in the grow-bed.  Additionally, the fish are growing in size and seem to be happy and healthy in their environment.  The constant cycling  of the water through the grow bed media has kept the aquarium clear and clean.

The week before spring break was interesting to say the least.  On Tuesday morning, March 11th, we were greeted by  a fish tank with no water, a flood in the basin holding our system, and a malfunctioning pump.  Fortunately, no fish died overnight.  We fixed the problem quickly by removing the pump, filling the tank, and leaving the fish with an aerator.  After some troubleshooting, we found out that there were a couple issues.  First, the pump did not create enough water pressure to start the siphon.  Also, our box leaked and nearly drained the system of water.  To solve the leakage issue, we resealed the box and attached window flashes to the bottom to funnel any more leakage back into the fish tank.  As for the pump problem, it appears that the best solution is to use a second pump to create a higher water pressure at the end of the wet cycle to begin the siphon.  Unfortunately, this meant that the seeds could not be put into the system before spring break, but they were left to continue growing in the bag (Joe Steinmacher)

As with any new system, there is always a period of adjustment, troubleshooting, reengineering and so-forth.  Our initial plan to have two pumps- one for normal duty and one for emergency backup had to be modified.  After our “catastrophic failure” the solution was to leave the first pump on all the time, set to fill the grow bed approximately every thirty minutes.  At the thirty minute mark, the second pump is initialized and allowed to run at full-flow, creating a surge that puts the bell siphon into operation.  This second surge pump only runs long enough to get the Bell-Siphon to start.  Should the grow bed happen to drain before the surge pump turns off, we’ve found that the siphon continues to operate until the surge flow ceases.  At that point the siphon sucks air and the process is extinguished.