In the last few posts I’ve briefly mentioned some things that need to be fixed or improved like the air system and grow cabinet. The soaker hose was a great idea in theory, but in practice it clogged often and was not practical to clean the 30′ lengths inside the greenhouse. The grow cabinet lighting wasn’t cutting it and our seedlings were still stretching.
Air system upgrade
What first tipped me off about the lack of air in the system is that the backend step of cycling the tank and processing the nitrites was taking much much longer than the ammonia step. I noticed the small sections of hose we had in the digester were getting clogged frequently. I initially shrugged this off because I thought the water was just dirtier (it was). This prompted me to check the bed air lines and the airflow was indeed super low.
I decided to do it right and sat down to plan the new air line setup complete with air stones under every raft which would receive even amounts of air from a manifold. I purchased 12 of these air stones and piped them into the 12 slot manifold that was included with my large pump.
I have since hooked up the last 2 lines seen missing here on the right.
I also added two of these ceramic air diffusers to my fish tank to help out with the o2 levels downstream in waste processing. These are a bit more pricey, but they put out tons of bubbles and need virtually no maintenance. I ran all the airlines under the floor and up to each position to keep the upstairs free from anymore obstructions. I didn’t realize how much my large air pump was struggling to push air through that soaker hose. It runs much cooler and quieter now.
I have since decided to hook up my backup air pump into this setup as well to try and remove the o2 levels variable from my plant troubleshooting. I now have 220 lpm of air being pumped into the system. I believe this is way overkill and will probably remove the second pump if it turns out that the air isn’t the issue.
Grow cabinet upgrade
My original cheapo blurple lights from Amazon just weren’t cutting it. My plants still got stretchy and the effective spread on the output is pretty narrow. I decided to make a small light with the same cob leds I used upstairs for the main grow beds. I was concerned about the heat buildup in the small cabinet so I thought it would be a perfect opportunity to try some low budget water cooling. I’ve always had this paranoia that my pump will quit and my stuff (or building) will burn up. For a redundancy fallback I sandwiched the cooling block in between the cob and a heatsink. The water should still circulate via convection if the pump quits albeit at a much slower speed.
I then piped in a small aquarium pump that I got for free (yay!) and used a small paint can for a reservoir/radiator. It actually works really well! Over a 12 hour active period the paint can gets up to around 75 F and the cobs stay around 100 F. I run the lights at half power and since the cabinet is lined with shiny bubble wrap the plants get around 35,000 lm. This is roughly the same as a sunny day up in the dome. I did install a 4″ fan inside the cabinet to pull air in if the lights do get too hot, but so far I haven’t had to turn it on.
Those are the latest upgrades, but there’s always tinkering to be done. Now that winter is approaching, I’ve been struggling with the humidity in the dome. With the colder weather comes colder temperatures which lowers the dew point (cold air can’t hold as much moisture) and I have condensation dripping everywhere.
I need to install a backdraft baffle in the ceiling where my exhaust fan is to keep the cold out. I did install a crappy diy dehumidifier loop that just circulates water outside to cool the coil inside, but i don’t think it’s quite cold enough to work. My coil outside is probably too small as well. Right now I’m using a plug in dehumidifier until I come up with something better. I have a feeling my ventless natural gas wall heater is adding a decent amount of water vapor into the air, so I’ll probably swap that out for a direct vented version at some point in the near future.