1. FISH: The presence of fish in the water lowers the amount of dissolved oxygen in the water, which should be accounted for when calculating the net productivity of each of our systems. Since fish are not producers, they do not contribute to the net productivity value. If one tank has more fish than the other because one died, then the dissolved oxygen levels may go up even if the net productivity does not change.
2. TEMPERATURE: We have two tanks in our aquaponoics experiment, one 73 degrees and one 86 degrees. The tank that has water that is 86 degrees will have less dissolved oxygen and therefore a lower net productivity than the tank that has 73 degree water. So far, this has been consistent with our results because the plants of the 73 degree tank have sprouted earlier and grown taller (increased in biomass) than the 86 degree tank plants.
3. LIGHT: The amount of light that the plants receive will also affect the dissolved oxygen levels. Light increases dissolved oxygen levels and by extension increases net productivity. We are leaving the lamps on for 17 hours a day and off for 7 hours. The light should have equal effects on the net productivity of each system.
4. TESTING FOR NET PRODUCTIVITY: Eventually, we will have enough basil to measure the biomass of the producers on a scale. Once we do, we will also perform the methods from this (http://www.biologyjunction.com/ap_sample_lab_12_dissolved_oxyge.htm) lab to find levels of dissolved oxygen in each of the tank.
Initial levels: 1/19/17
Nitrate: 0.0
Nitrite: 0.0
pH: 5.4, however that is most likely because the test strips that we used were old. Now we use pH test strips that we bought and our results were way more neutral.
ammonia: 0.0
Current levels: 1/27/17
Nitrate: 0.0
Nitrite: 0.0
pH: 6.8
ammonia: 3.0