Sorry, I have not had a chance to test my tap water. I do not think there is a problem there though, as I do not have a problem with my nano.
Here is a random question. When reading the results in the test tube, do I hold it up to the light and compare with the light going through the tube? Or hold it up to the card, blocking the light from coming through.
I did a 50% water change last night and tested after. With the tube held up to the light, the result looks like 20 to 40 ppm. With the tube held up to the card so light does not pass through, it looks like 80 ppm.
As for cleaning it out... I did something like that when i had a brown algae out break. I took every plant out and cleaned them, and thoughtfully scrubbed everything. I also added about 20 plants, and 4 Otos. Never had that problem again.
Right now I am dealing with what looks like green hair algae. Its on my driftwood and any plant or object that gets 3 to 4 inches from the surface.