Couple of things, "restrike" is indeed the amount of time it takes a bulb to relight once extinguished. However, many people in the fishkeeping world also use it as a term to describe the light that is lost due to being reflected back into the bulb it originated from, so you're both right.
With a spiral CFL you lose approximately 1/3 of the wattage to this type of restrike.
SO:
with 3 bulbs at 27w each you have a total wattage of 81. Minus (about) 1/3 for the restrike issue you end up with 54 effective watts.
54 watts over a 20 gallon tank works out to 2.7 WPG. Fairly high light, if you are not running at least DIY co2 you will have constant algae, I would be willing to wager you would have just fine growth if you completely remove one bulb and just run with two. And co2 or flourish for sure.
Either way, you definitely want to get rid of the 2700k bulb, it is not helping anything but the green water.