It’s been quite a while since my last update, and I’ve had a lot of developments, so here we go!
The AquaFarm from Back to the Roots had been making a decent amount of noise as the air pump rattles against the plastic container. I tried to adjust the foam insulation pad, but it was difficult to keep the thing quiet. I was away from my apartment during my trip to Burning Man, so I moved the betta into a different tank and had a friend take care of him for me. The wheatgrass grew well, but the basil and other herb didn’t grow very well. Right now the system is empty, and I’m planning on starting it up again in the next few weeks.
The 105 gallon system at my friend’s apartment is still slowly moving forward. My friend is taking a trip to Nepal, so his room got a new owner. My buddy Saqib is going to look after the aquaponics system from now on, and I’m glad that he’s excited about it. The seed plugs (coco coir, I think) started developing a white mold, so I broke off the plugs and planted the seedlings directly into my grow media. I also installed a drain plug into my bell siphon to keep rocks from messing up the drainage cycle. Pogo had bought 6 full grown tilapia for the fish tank before I left for Burning Man, but only one is still living. I would have preferred to start with fingerlings, but one large tilapia will do fine for now. His name is Hercules. I think Saqib and I are on the same page, and want to eat Hercules and fill the tank with smaller, decorative fish. I also want to cover the sides of the system’s frame with cloth to keep sunlight out of the filter and fish tank. Some algae grew inside the filter, that I need to clean out, so hopefully the lack of sunlight will fix that in the future. The pH seems to be slowly, but consistently dropping, so I’ve had to add pH up a few times. I’m not sure what’s causing the pH drop, yet. We’re working out the little kinks in the system, so I’m excited to see how it works out. I’ll update when we have some new developments!
Recently, I spoke with a hydroponics expert, Dan Sypolt from Garden Indoors, a hydroponics store in Bristol, PA. I had come to the store to buy 190 liters of expanded clay grow medium for the 105 gallon aquaponic system for my friends apartment. Instead of just selling me their product, Dan really helped me decide upon the best way to approach the system that Im working on (I ended up not buying anything at that time). He brought up some great points that I dont hear being discussed very often in aquaponic forums that I read. His advice has led me to re-planning the system Im building, and I think it will be a more robust system with this new design.
First, Dan suggested that typically, hydroponic systems are only flooded with water around 4 times during daylight hours. My windowfarm had been trickling water 24/7 which over-watered my strawberries. I have read many suggestions for a 15 minute flood, every hour. Dan suggested that this was probably too much (at least from a conventional hydroponics perspective). Im going to start the new system with a 15 minute flood every 3 hours, and see how it works out. The less pumping, the more energy saved on electricity.
You might be thinking that flooding the system every 3 hours will not provide a moist environment for the bacteria to grow in my media beds. This leads me to Dans second suggestion. In the store, there were several hydroponic setups that were similar to my aquaponic setup, except that instead of having one large grow bed filled with media, the grow beds were holding potted plants, and the grow pots were filled with media. This used a lot less media than filling the entire grow bed, which will save you money. The grow bed is essentially acting like a flood table. This allows you to move the plants around easily without disturbing the roots. You can also remove plants easily, and it also makes the grow bed much easier to clean. All the solid waste that builds up in the bottom of a grow bed can be a smelly pain in the butt to clean. This isnt a problem with this setup. You dont have to worry about media guards for your plumbing, because the grow media never touches the plumbing. The flood table would look something like this:
Now, you may be thinking, "What about filtering the water? What about the bacteria?" The grow bed in a flood and drain system typically acts as a filter for solid waste, as well as the location for bacteria growth, essential to aquaponics. If the water is not being pumped into the grow media, than where is the bacteria growing, and how is the solid waste filtered. For this, Dan suggested using a typical aquarium filter. There are several filter types available. If youre using an aquarium, a hang-on-back filter is fairly inexpensive, but may be less reliable than other filters.
A canister filter is usually a little more expensive, but more durable. Ive chosen to use a Canister Filter for the 105 gallon system that Im building (pictured below).
Another filter type that Dan mentioned was a Wet/Dry Trickle Filter. This is like having a separate, smaller media bed specifically for growing bacteria. It can be attached to an aquarium, but they seem very bulky.
The filter that Dan suggested would work best is a Fluidized Bed Filter. These are highly efficient biological filters that have enormous bio-load capacities and take up very little space. They are similar to a wet/dry trickle filter with extremely small media (typically sand), but air is pumped into the media causing it to flow around. This flow causes the bacteria to be "bumped off" the sand grains, and more bacteria grows in its place. Bacteria can adapt very rapidly to increases or decreases in bio-load. With such a small media, the surface area is huge, allowing for an enormous amount of beneficial bacteria. Heres a cool video to demonstrate how it works.
So, with all this in mind, I think this is a better way of designing a flood and drain aquaponic system. The canister filter cost me about $100, but Im saving at least $80 that I would have spent on expanded clay pellets. I havent researched the other options extensively to write about all the pros/cons of different filters, but the canister filter seemed durable and efficient. As for the system design change overall, I think that the pros outweigh the cons. What do you think?
