Aquaponics experiment 2013 week #3: more supports, more gravel, working siphons, added fish and plants

Posted on May 31, 2013 in DIY

This was one heck of a week for progress on my aquaponics system! I got so much done that when I was writing the title for this post I was surprised by how much stuff had happened. Not only did I get the water circulating really well, but I’ve added both fish and plants!

Additional additional supports

Even with the supports that I added last week, the one fully loaded barrel was still sagging quite a bit. Furthermore, the 4×4 scraps that I added right in the middle of the structure were blocking access to the barrel bulkheads, making it impossible to construct siphons to drain the beds. To solve both problems, I added more support beams under each of the grow beds and removed the center posts. Now the barrels right nice and high and don’t sag at all!

Washing gravel – day 2

In my research on aquaponics I’ve found that many people choose to wash the pea gravel before putting it in their grow beds. However, all of the methods I saw seemed like a LOT of work and transporting the gravel back and forth. To save myself some time and work I simply added one bag of gravel to each grow bed at a time and ran tap water through it all, draining the water directly through the bulkheads to external buckets, which I dumped elsewhere.

Installing the loop siphons

I had a little bit of trouble getting my siphons set up at first because the bulkhead I got was intended to hook up to 1/2″ tubing. Unfortunately, I used that same tubing for the inlet lines, so I didn’t think that the beds would drain fast enough to overcome the water coming in.

I learned that a piece of 1″ ID clear vinyl tubing fits very tightly on the entire outer rim of the bulkhead’s threads, which would allow the grow bed to drain very quickly. However, the large tubing is impossible to bend into a tight loop with no kinks to function as a loop siphon.

After a bit of fretting and frustration, a friend pointed out that this clear vinyl tubing appears to be designed in such a way that the next-smaller diameter of the same tubing fits perfectly and tightly inside of the larger one. So I decided to use a small ~2″ section of the large tubing as an adapter on the bulkhead, and some smaller tubing to create the loop. And voila! We have working loop siphons!

The grow beds take about 2 minutes to fill up and another 2-3 to drain. Super fast, but totally fine.

This is probably my favorite part of the system, it’s almost like magic! Once the water reaches a certain level in the grow bed, it pushes all of the air out of the loop, which creates a powerful sucking force (I say magic), causing all of the water in the grow bed to be dumped out very quickly. Once the loop starts to suck in air instead of water, the siphon stops and the process starts all over again. It’s so fun to watch, I even made a video!

Adding some fish

Last week I signed up to buy 5 channel catfish from a dealer that works with my local Orschelns farm supply shop, and went to pick them up on Tuesday afternoon. I quickly found out that the flyer / sign-up sheet that they provided for customers was pretty inaccurate and ultimately pointless (they were not given any returned flyers to check orders against).

Since I was expecting to be cycling my system for another couple weeks, I only signed up to buy 5, so that they could add some ammonia to the system. When I told the dealer I only wanted five, I didn’t get a super friendly response. I was instead told that the minimum order was 25 (not indicated on the sign-up sheet). Well, they were cheap, so I bought them anyway.

Also on the sign-up sheet, they said that I was expected to bring a bucket of pond water to transport the fish in. Turns out that wasn’t correct either – they just pumped some fish into a clear plastic bag and sealed it with plenty of air.

I felt that adding all 25 fish at once to the system could overload it with ammonia within a couple of days and cause some real problems, so I opted to keep about half the fish in a bucket next to the fish tank for the night. To spare you from the gory details, I now know that fish cannot survive in a bucket overnight.

Adding plants

I decided to add plants only two days after adding fish to my system for the simple reason that starter plants won’t be easy to find in another few weeks. That and they are really cheap!

In the left grow bed I planted six lettuce plants and six broccoli plants. In the right bed I planted five cucumber plants, one squash plant, a cherry tomato variety, a jalapeno variety and some eggplant.

All but two of these plants should stay low to the ground and grow broad flat leaves, which should help it stand up to the fierce wind we’ve been having. The tomato and jalapeno plants I tied to a stake, just in case.

From what I understand, adding plants should help to stabilize the system a little bit and help to soften the effects of spikes in chemicals as the system finds its equilibrium.

Chemical test results

Now that all the “hard work” is done (installing the structure, the siphons, the gravel, etc), it’s just a matter of letting nature do it’s thing and find an equilibrium. This is the reason I’m referring to this whole project as an experiment: in three months, I either will or will not have fish and/or plants to eat. From this point on, most of the work will be in monitoring the health of the fish and plants and making sure that the system is still running each day.

I will be using my API Freshwater test kit to test various chemicals in the water at least once a day. Specifically ammonia, pH, nitrites and nitrates. Too much ammonia, pH or nitrites is a problem, each with their own solution. Here’s the game plan:

  • Ammonia spikes (bad)
    Cause: probably due to fish waste not being completely processed by bacteria and plants.
    Solution: Change out at least 1/3rd or 1/2 of the water in the fish tank with fresh, de-chlorinated water.
  • Nitrites spike (bad)
    Cause: the bacteria that converts the fish waste (ammonia) into nitrites is present and doing it’s job, but the other bacteria that converts these toxic nitrites into healthy nitrates is not present and doing it’s job.
    Solution: not totally sure. Probably a partial or complete water change.
  • Nitrates spike (good)
    Cause: all of the necessary bacteria is present and working. This is the good stuff that both the plants and fish love – more is better!
  • pH too high (bad)
    Cause: not actually sure. I hear from my local fish aquarium dude that my city’s water is just high in pH in general. I don’t think the plants or fish contribute to it much.
    Solution: add a couple cap-fulls of General Hydroponics’ pH Down formula

And here are my most recent test results from Friday morning (remember that fish were added on Tuesday and plants were added on Thursday):

Friday - 05.31.2013 at 11AM

from left to right:

  • pH: about 8.2. Not ideal, but not terrible.
  • Ammonia: about 2ppm, which is NOT good. The fish will live, but their waste is not being processed perfectly yet. Will probably do a partial water change on Monday.
  • Nitrites: about 0.25ppm. Pretty good!
  • Nitrates: about 40-80ppm or higher – awesome!! The fish and plants will really love this.

All in all it looks like the experiment is going along quite well. None of the fish in the main tank have died, and actually seemed very feisty today when I fished some out to look at. It’s too early to tell how the plants are doing, but next week I should start seeing some kind of difference.

Now it’s time to sit back and see what happens!