I live in Central Texas. I've been fertilizing a 28 ac. pond for six years. It has really made a big difference. I use a 7.5 horse outboard on a 14' flat bottom boat. I hook up a syphon pump to the motor fin and feed liquid fertilizer through a hose. It works good and I always get a great bloom. I tried granular fertilizers 6-10 years ago and got nothing. I also have a 1 acre pond that I use a 12v. sprayer to fertilize. I catch a windy day, set the sprayer on the bank pour in 10 gal. water, 1-2 gal. fertilzer then another 10 gal water. Mix well by spraying nozzle back into the tank. Hook it up to a battery, put nozzle in a forked stick and leave it for about an 1 or so.
Your 5.5 acre lake will be fun to manage and this bulletin board along with Pond Boss will really help you do it right.