I am learning a lot about our Aquaponic system, perhaps most of all that it needs to be warmer to operate successfully. I have also learned that sometimes a little bit of chemical can have a big impact. At this point I think I will wait until the system warms up naturally and finishes cycling before adding fish, but for next winter I need to find either a way to heat the greenhouse directly, or a more powerful solution for heating the fish tank water.
For any Aquaponics veterans reading this, I have some questions at the end of the post and would welcome feedback in the comments section.
Fully Operational Aquaponic System
At this point all of the infrastructure is set up and operating correctly. The 200W LED lights are hung, timers are operating and all the water is flowing correctly.
Fish Tank
The 180 gallon tank is full, but bowing. This is not getting worse, so I am not too worried about it. I am considering how to insulate the fish tank, and this may lead to also bracing the side. I have been very surprised at how fast the water temperature in the fish tank adjusts in reaction to the ambient air temperature. The three heaters on the lower right can't seem to keep the water more than 10 degrees fahrenheit above the air temperature.
I have also been surprised (and frustrated) getting the pH right. Our tap water is about pH 7.8. I added what I thought was a little pH DOWN to try to get it closer to 7.0. I way overshot, and suspect I took the pH down under 4.0. It has taken more than a full bottle of pH UP to restore proper pH. I was surprised that the pH UP and pH DOWN chemicals had very different impact for the same amount of added chemical. (Both chemicals are from the same company, Pondcare.)
Because of the low water temperature, the cycling is going very slowly. Nitrites are currently up to .5 ppm, but the nitrification process only seems to work when the water temperature gets above the low 60s. In Virginia, I am expecting to see the greenhouse warm enough to consistently support this water temperature by mid/late February.
Very Chilly Water
We had a spell of warm (65+ degrees fahrenheit) weather earlier this week and the water was up to 68 degrees. I have found that when the sun is bright, even though it only shines on the greenhouse for about 2-3 hrs, it has a big impact on the temperature. The high temp in the greenhouse in January was 91. However, when the air cools off, the water cools off quickly. It when from 68 to under 60 in 24 hours.
In addition to temperature and chemical challenges, I think the lights may be too close to the plants. I planted two small perennials from Logee's Greenhouses about three weeks ago when I installed the lights. The one on the left is Curry Plant, and the one on the right is Kaffir Lime. So far they have not died, which considering the cool greenhouse and lack of nourishment is not bad. However, the leaves closest to the lights are starting to discolor, especially on the Curry Plant. Right now the lights are hung about 18" above the surface of the grow medium. I am going to try raising them 6" and see if that helps.
Based on the current status of the Aquaponic system, I am working through the following questions and welcome input.
1) Should I brace the fish tank so it does not bow so much on the right side?
2) Should I insulate the fish tank, and/or make an insulated cover?
3) My original thinking was to heat the water in the fish tank, and let the water warm the air in the greenhouse. I am revising my thinking and for next winter leaning more to a combination of heating the greenhouse itself, and insulating/heating the fish tank. Does this make sense?
4) What are the minimum winter water and air temperatures to keep the fish and plants healthy and growing?
5) How far above the plants should the LED lights be hung?