All great suggestions, but also very different.
Regarding your lights being on too long, I am not familiar with the reasons for that recommendation and
will not comment.
information is that my ph=7.6, temp=80, kh=140, substrate=75 pounds of
fluorite, no additives or supplements provided.
The diy CO2 seams to be working quite well as all of the plants seem
to be growing nicely and are pearling and misting oxygen bubbles.
Now here's what we can piece together:
60gallon tank, densly planted
160 watts flourescent lighting (reflectors?), 10 hours per day
External power filter with bubble-over return
pH=7.6, kh=140 yields a CO2 level of 5.9 ppm at the time you measured using the calculator at
Probably higher in the morning, lower at night.
You have not mentioned fish load or Nitrate level. But I'll bet that Nitrates are near zero, and other
nutrients are low as well, given that you are injecting CO2 and "all the plants seem to be growing
nicely". They are using whatever nutrients are available in your tap water.
1. Read about PMDD he
2. Measure Nitrates before you start dosing KNO3. It's not safe to add nitrates
to a tank with fish unless you know the level first. The target range for a
planted tank is around 10ppm, you are probably under 5ppm.
3. High iron is indeed a possible cause of green hair algae. It certainly is in
my tank. Contact your water department to request a water quality report,
or test your iron. It seems unlikely that you have excess iron if you are not
adding trace fertilizers AND your plants are growing. But if there is a high
level in your tap water, that could be the source.