Betta Fish (RWI1) (Final Week)

The Betta fish in the lab has not died yet and neither has the plant. They both seem to still be healthy and they fish is still isolated from the others by a cardboard sheet. And it is still very close to the window so it can receive lots of sunlight. The stems of the plant has still been growing rapidly tall but I also noticed that the plants that are right against the window have even taller stems and more leaves.
I did notice that the water quality was not as usual. There seemed to be a build up of algae on the sides of the jar and especially at the bottom where the substrates are.
The bubbles formed at the top of the jar has gone down but is still there. The fish it's self is less active than it was last week, it spent a lot of time at the top of the jar but was moving much slower than usual. This could be due to the fact that the water quality has changed. This could be because the water it's self has not been changed and the jar not cleaned.
According to the results the plant length is 25cm and the root length is 60.5cm.
The specs of the water is as follows:
NO3- 0-10; NO2- 0; GH -0; KH- 3-6; pH- 6.4