Do you live in the Augusta area?

Was this spectracide a liquid or a dry product? Because you said you bought a spreader. Typically that word is reserved for the equipment used to apply dry products. If you applied a dry product, did you read the directions where it said to apply to a wet lawn?

The best ways to keep weeds out are the following
1. Grow a very dense turf. This is more complicated than it sounds.
2. Water deeply and infrequently. Deeply means a full inch all at one time. This might take hours (and hours) to accomplish. Infrequently means no more often than weekly during when the temps are in the 90s. When it cools off water much less often.
3. Mow at your mower's highest setting...with the exception of bermuda, centipede, and creeping bentgrass which should be mowed at the lowest setting.

Numbers 2 and 3 don't cost anything and will keep the weeds out of the yard. Number 1 will cost you some fertilizer and if you have fescue or rye grass, it will cost you some seed.