Poly uses a 9 watt fluro. Careful with your lighting, it will introduce heat that you have to provide for, your crop does not need much light, but the light you give it should be across the entire growing field, if not you will have mushrooms that bend to the diminished source. Your fruit will be elongated and your caps will be small. um.... I checked, the elongated fruit weighs no more than normal fruit - so don't bother looking for extra weight through light maniuplation.
Mushroom fruit start as primordia - little mycelial knots that turn into tiny pinheads. They will grow somewhat slower than they do at the end, the reason for this is that to a certain point the cells actually accumulate within the fruit, at a later stage the cells simply expand - you will see something wonderful, you will see your fruit grow before your eyes but the weight will not really increase after a certain point.
(really, you can look, go down to get yourself a beer and half an hour look again and you will see your crop larger, noticibly so).
This is why for the most part you want to harvest just before the veils break, in actuality, your weight will not be much different nor your potency changed after a certain point before the caps even being to open but, well, it is too much fun to watch them continue to grow. in the pics you saw you will see that I waited far too long to harvest. The spores can actually be dangerous to your health and at a certain level you will see vast accumulations of them everywhere. Oyster mushrooms can cause respratory problems and I have had to wash down the walls of my house because of what must surely have been several ounces of oyster spores.
BTW you don't have that problem with shaggies as shaggies autodigest, they turn to slime and the slime captures the spores making a black sticky mess.