First off, it's important to make sure that your pool pump is running long enough during the heat of the day. As a guideline, the pump should be run roughly 1 hour per 10 degrees of water temp. For example if the water is 80 degrees, the pump should run for 8 hours. The larger your pool, the longer the pump should be run. The goal is to have the water turn over 1.5 times per day.
Assuming the algae is of the green or yellow variety, here are some suggested steps you can follow:
1) Make sure pH is within the acceptable range of 7.2 - 7.8. Adjust if necessary.
2) Thoroughly brush the entire pool interior surface. Leave the brush in the pool during the remaining steps.
3) Clean the filter and monitor any appreciable increase with the filter pressure. Set the pump to operate at least 24-hours.
4) Add a double dose of shock: 4 - Dark Blue chlorine shock pouches per 10,000 gallons of pool water.
5) A Copper-based algaecide is very helpful when used in conjunction with a shock treatment in eradication of resistant green or yellow algae. Add the algaecide the following morning after the shock treatment. ( purchase the algaecide locally)
6) Once the algae has been removed and the water is clear, clean the filter again to remove collected dead algae.