One of the most common problems in swimming pools is algae. Some seasons it seems you can spend half of your time fighting algae in your pool instead of just enjoying your pool. Algae needs several elements to grow in your pool. The one I am going to focus on here is phosphates. Phosphates can come from several environmental factors such as excessive rain or plant debris. If you can eliminate or severely reduce the amount of phosphates in your pool, you will be able to stop algae from growing in your pool.
The best way to do this is to use a phosphate reducer such as Natural Chemistry's PhosFree. I have used the commercial strength version of this product as I've linked to here and have had good success.
One capful per 10,000 gallons per week should be a sufficient maintenance program to prevent algae. You should also add a 1/2 capful after any heavy rains. Also, try to remove any plant debris in your pool as soon as you can. Allowing it to sit in the pool and breakdown can increase phosphates and also stain the bottom of your pool.
If you already have an algae problem, you can add 1-1/2 capfuls per 10,000 gallons and it should kill all the algae in the pool. If not, try again in 24 hours with 2 capfuls per 10,000 gallons. Please note, that when using PhosFree to kill existing algae it will result in lots of dead algae on the bottom of your pool. If you use your pool vacuum to clean this up it is going to end up clogging your filter so be sure to clean your filter thoroughly once you have completed the algae clean up.
Lastly, when using PhosFree to prevent algae I have observed that the PhosFree does coat the filter so it can kill all the algae in the water, resulting in higher filter pressure and a reduction in the water flow.........so you can clean your filter off after 2 days of using the PhosFree to allow your filter to function properly again.
I hope this tip is helpful. I'd love to hear feedback from pool owners.