Howdy folks! Welcome back to my blog series on aquaponics. In last the last post, titled “It’s not about the magic, it’s about the normal” I discussed the need for beginners in aquaponics to understand that it is a garden and has all the same needs of any other indoor garden. I also talked about one of my own early mistakes that arose from not really understanding how to be an indoor gardener.
One of those things that I do try to keep in mind is that any success of mine in aquaponics is a result of “standing on the shoulders of giants”. Which is why I’m writing these blog posts. I’m hoping to help other folks who are interested in this remarkable sustainable farming technology. I’ve made some mistakes and I’ve tested some theories, and I want to make sure that anything I’ve learned or proven or tripped over winds up out in the collective record of the Internet community.
The lights are off, the pumps have stopped, the lab is closed
So after 9 months or more of continuous and flawless operation, including a small harvest of beans and sweet peppers, the indoor system is no more. It was a surprisingly difficult decision to make, but there were some good reasons for it.
The first pair of reasons are pests. Fish are notoriously touchy about anything that will quickly kill anything else. So, between an experiment with aquatic snails gone wrong and an infestation of migratory aphids, there was a requirement to do some serious “kill stuff” work.
However, soaps and copper-based kill products will destroy the nitrobacter in the grow media. Even if they don’t wipe out the entire colony of beneficial bacteria, an aggressive spray program will contaminate your water and either seriously injure or outright kill your fish.
“But it says this soap is bio-degradable?”
That means that within 30 days it will stop being soap and turn into something that won’t destroy the gills on the fish. However, as long as it is still soap, it can and will destroy the gills on the fish.
The original idea had been to use snails as aggressive bio-converters of fish waste in the sump of the system. As waste-rich water flowed from the fish bin to the sump, the snails would convert that into something more useful.
It worked. In fact, it worked so well that I had a population explosion of snails. Which was kind of cool, at first. Snails are spiffy little things, and I like them. Unfortunately, there are three issues with snails in aquaponics I did not know — I should have done the research first.
While the snails are incredibly good at converting uneaten food and fish waste into a rich stream of water-soluble products, they also create a ridiculously fine silt. So much silt was being produced that it was plugging the particle screen on my pump, sometimes in as little as 3 days.
As water flow decreased, then the bell siphons would “lock” in a state of balance where the amount of water coming into the bed was exactly equal to the flow out … and so the siphon would never stop running. Instead of a flood-and-drain regime, now it was a trickle-flow wicking bed. Where I depend on the flood-and-drain cycle to filter water physically and chemically, that was bad.
This meant that as the snail population increased, the maintenance associated with the system doubled or tripled. Not a good trade.
Snails are stupid. I know that seems obvious, but the effect is that they will aggressively over-breed until the environment cannot support the population and there is a significant die-off. However, the sump of my aquaponics system was a nearly perfect environment for them.
That meant the environmental ceiling was high. Very high. That, in turn, exaggerated the silting problem more and more.
Snails, it turns out, are common carriers / life cycle hosts of parasites that can do serious damage to fish populations. In some cases, those parasites are actually dangerous to human health. Thus, in commercial aquaculture, snail populations are frowned upon by health inspectors. Ergo, even if you know your “snail culture” is “clean”, it just causes paperwork grief.
The combination of these issues means, for me at least, that no matter how good a job they do of cleaning out the sump tank, they just aren’t worth the hassle. The problem is that if you miss 2 eggs in a system … you will have a brand new snail problem in a matter of a few months. Sterilization of the system is pretty much the only option.
Aphids are a sap-sucking insect that will literally drain the life out of the plants that they infest. Like snails, they do not self-regulate their population. They will expand in numbers to consume everything available as food and then either move on or die out en masse.
They are avian, and rapid populators. If you find one aphid, you likely have a hundred and that will be come a thousand and so on with remarkable swiftness.
I had the misfortune of having some come in on a herb I bought from a local vendor. By the time I realized I had a problem, it was a huge problem.
Aphids, interestingly enough, are easier to deal with in a situation like a greenhouse than indoors. You can import beneficial insects, such as ladybugs, lacewings and parasitic wasps to prey on them. A couple of ladybugs will keep a square meter or so of greens aphid free. As well, biological kill systems, such as fungi that are deadly to aphids but safe for other garden life are much easier to use outdoors.
Indoors, the options are much more limited, particularly when soap-based sprays are off the table. A common answer within the basement aquaponics community is take the fish out of the system for a few days, use an aggressive soap-based foilar spray program, and then do two full water changes a day or so apart before re-introducing the fish.
If that doesn’t work, then you have to remove all the plants and sterilize the system and start over.
One thing was becoming more and more clear as time went on … the ebb-and-flow process was flexing the plastic shelves to death. The weight on the shelves changed by 15Kg / 40 Lbs every five to six minutes. This constant process was clearly rapidly aging the shelving unit and even the shelf that had been load-distributed by a platform of 2×6 boards was succumbing.
So, my Father’s Dad present this year from my wife was a brand new steel and wood shelving system with twice the load capacity per shelf. To be able to put the old system onto the new shelves, it was going to have to be drained, disassembled and then rebuilt anyway.
This project was, from the outset, a science experiment. The objective was to theorize, to build, to test, to learn. In its current configuration and age, the learning and science had been achieved. I understood both indoor gardening and aquaponics systems much, much better than I had.
The system had be a remarkable success. No “crash”, fish which had increased their mass five times in less than a year, a couple fistfuls of edibles from the plants, and plenty of biomass. Water quality throughout the process was very good.
I verified some ideas about siphon design and discarded others. I learned heaps about the value of just “splashing water around” as a way to ensure idea oxygen content.
Once you’ve paid the gravity bill, you might as well get as much as you can out of the cost; don’t pour it, splash it.
I built this and it worked.
It might seem like a “yeah, so?” statement, but for me, it is incredibly important. Having vetted the whole thing at the scale of a moderate aquarium, I can now go on to build a system with over 1500L / 335Gal of water in it. Eventually, there will be 5 square meters of growing area and 40Kg / 100Lbs of rainbow trout in it.
That system, by the time it is done, will cost me a thousand dollars to build in materials. That leaves out my time in research, development and construction.
Oddly enough, I wasn’t much interested in spending that kind of investment until I was sure that I could make a trial-scale version work. The confidence and experience gained are invaluable to me.
Once the greenhouse scale version works, then I’ll start thinking about the next version … a commercial mini-farm system run as a CSA or supplying the local restaurant with organic produce.
The lab may be closed, but the learning continues
I’m still doing research and reading as I work through the fall prepping the greenhouse I built for the new aquaponics system. I’m experimenting with ideas, and getting prepared to build a 50mm / 2” diameter scale bell siphon system.
50mm / 2” diameter pipe is the size that the greenhouse system will work with for everything that water has to flow under gravity through. The line from the sump to the grow beds might be 37mm / 1.5”, depending on the pump. Everything else, however, will be 50mm / 2” diameter so there is no risk of flow restrictions.
One other thing I have learned in all this that is also very important. Doing this makes me feel good. It’s a very positive experience; building, growing, learning, doing. It is a wonderful hobby and I’m looking forward to the next steps.
Once the greenhouse system is operational, then I will be building a brand-new basement system. It will incorporate all the lessons I’ve learned, and if all goes well, will lead to a set of plans and an ebook.
I’ll keep you posted on how it goes!