Romaine, butter crunch, and red oak lettuce doing well!
After completing the build out and grow beds, we’ve beens spending a few weeks learning the ins and outs of raising fish and diagnosing different symptoms with our plants.
I’ve read over and over “don’t over feed your fish”, “adjust your ph slowly”, and so on. Of course I didn’t heed this advice and was too impatient. The silver lining is now I know what the wrong thing looks like and how to resolve it.
Issues we struggled with or created
- Cycling the system
- Super high nitrates and nitrites
- fish dying
- plants dying
Cycling the system
We decided to cycle the system with fish rather than without. We did this against all recommendations mainly because we had no experience caring for fish and wanted to get a feel for it. Being a newbie at raising fish, I was excited to get them on a feeding schedule so they can start growing. Turns out I overfed them and the system suffered a massive bacteria bloom. I held my breath and most of the fish begrudgingly weathered the storm.
After several water changes over the next week or so, the bloom let up and our ammonia disappeared as well. The first stage of cycling was complete! This all went fairly quickly and I was expecting the nitrites to disappear in a timely manner as well. Boy was I disappointed.
Super high nitrates and nitrites
Chlorosis caused by excess nitrogen and probably an iron deficiency
Right around the time our first cycling step completed, I was just starting to germinate some seeds and wanted to have some seedlings ready to start sipping nitrates. Since my fish water still did not have any nitrates, I diluted some hydroponic solution for my seedlings and subbed that in for normal water after they germinated. This was a huge mistake, but I hadn’t realized it yet. After I saw some roots poking out of the bottom of the rockwool cubes, I transplanted the nutrient soaked cubes into the rafts. This caused a massive spike in nitrates to around 350+ ppm overnight.
After many 50% water changes, I was unable to bring the nitrate or nitrite levels down. I suspect that the high nitrogen was locking out other nutrients because my plant started to struggle, while the fish were already sluggish. Along with my cycling issues, the frequent water changes constantly left me with 65 degree water and along with the high nutrient levels, I was super worried about the well being of the fish.
I finally gave up on trying to change my water clean and used Seachem Prime which contains complexed hydrosulfite salts. This product is essentially a reducing agent that is normally used to remove chlorine and chloramine as well as to detoxify ammonia. Another side effect is that it also lowers your other nitrogen levels. I had to double dose my system, but this brought my numbers down to a measurable range and resolved my nutrient lockout (or whatever was the issue).
While this brought my levels down, I was still having trouble finishing the last step of cycling my system and my nitrites slowly crept up. Also, I expected my plants to recover from what I guessed was nitrogen burn, but they still weren’t quite happy. After offloading the high nitrate issue, I started to notice that the mineralizer was hardly bubbling and examined the airstones. They were almost completely blocked (probably largely due to the bacteria bloom I had earlier). If those were blocked, the beds were most definitely blocked as well. I cleaned all the air hoses and poked more holes in my diffusers and the very next day everything was happy. My nitrites were almost gone, my plant were no longer wilting, and the water cleared right up. Low dissolved oxygen was most likely the main problem all along.
While I was working on solving our water issues, I made time to put up the trellises for our center bed vine crops. These are hanging from the ceiling and can be lowered if needed. The plan is to grow the tomatoes, cucumbers, and pole beans to the ceiling and lean the vine bodies back along the back of the roof. It sounds awesome in my head, but we’ll see if it works in practice.
pole beans, cucumbers, shelling peas, and tomatoes all making their way up!
The fish are happy
The water is green (but clear) from supplementing iron.
The fish are really happy now after enduring the entire cycling catastrophe. We started with 40 blue tilapia and are left with around 28 with six or so around 3-4 inches. We removed some of the insulation around the tank and kept the room warm and was able to raise the water temp to 75 degrees, we added more air, and our nitrites and ammonia levels are at zero. These guys are able to get their 3 square meals a day now and can be found zipping around the tank.
Now that things are stabilized and happy there are a few things that need to be revisited and started. The current method of using 1 long hose as an air diffuser turned out to be a bad idea with our limited space. With the diffusers being one large piece, we’d have to remove the entire thing to clean it leaving our plants O2 starved for the duration. I’m installing a more dispersed air diffusion system with airstones and regulators to help balance the beds. I’m thinking all my previous problems have been caused by inconsistent dissolved oxygen levels.
I’m really looking forward to getting grow lighting built and installed here in the next two months or so. The plan is to initially build/install 15 cob led lights. Each of these lights will be around 15,000 lumens and total 1500 watts. For comparison, your car high beams are around 2100 lumens. The days are already getting shorter and we’d like to keep our plants happy.