I went back in this thread, and I agree with
@DoubleDutch that the green in the photo does look like cyanobacteria. This is caused by excess organics in the presence of light. Nitrates is often (but not always) an indicator of organic matter. The white dots are not bubbles; not sure what they are, but I would suspect bits of solid organic matter that sometimes appears in aquaria.
Nitrate occurring within the biological system of the tank (as opposed to being present in the source water) can be dealt with by water changes, substrate vacuuming during the W/C, keeping the brown gunk out of the filter, not overstocking, not overfeeding, and fast-growing aquatic plants, especially floaters.