After doing some more research I decided to try adding some oxygen to the water. First, I washed all the lettuce plant roots. Many were rotten and just washed right off. I then placed airstones in each bed and ran a line to a central air pump for aquariums. Within two days the lettuce started looking better and I could see the tips of the roots were now white, although the temperature had not changed drastically. The plants that had started to bolt remained at the same height and started forming new leaves at the top.
This taught me a very important lesson: The dissolved oxygen level in water is extremely important, and it is highly dependent on temperature.
Here are some interesting insights:
- The higher the temperature of the water, the more it expands leaving less place for O2 molecules.
- Water and air exchange O2 molecules through the water surface, and this is the reason air pumps help since they agitate the water constantly, creating a space for this exchange to take place
- A slimy surface on your water will guarantee that very little or no O2 will enter your water