excess algae in aquarium

Question
Without much free time, I neglect the aquarium I have a water turtle in.  I change the filter more often than I add the proper water conditioners.  The floating turtle dock is caked with the darkest green algae I have ever seen; even the three snails are not helping.  My neglect doesn't help I know.  I am cleaning the tank and changing the filters and am trying to rid the turtle dock of this algae.  I really want to try to keep up on this better.  The lighting I use is the 50 watt used for exotic pets; however, it has blown about a month ago, and I have not been able to purchase the exact same bulb.  I have been using the traditional bulb used for all other household fixtures.  My question is:  How can I remove this algae without having to buy something expensive?  Can anything be used "under/over the counter" that won't harm our 4 yr-old turtle?  Thank you very much.

Answer
If you think he can tolerate it, try to cover his tank and keep the lights off for a couple of days.  Green algae uses photosynthesis to survive, remove the light source and it will die.  If it is thick, it may be beard or blue/green or hair algae and if that's the case, aside from removing the dock and boiling it, there isn't much you can do.  A lot of those algaes are very difficult to be rid of.  Do you have fish in there too?  How often do you feed?  If you feed less, it may help with the algae too..