How can I tell if my pool has a leak?
Simply fill a bucket with pool water and put it in the pool so that the water level of the bucket and the pool are the same. If the water level in the pool is lower than the water level in the bucket after one week, you probably have a leak. This method is relatively reliable, because the condensation behavior is the same in both tanks.

What can I do if I have algae?
Usually, algae is not hazardous to your health. A lab should analyze your algae, because it can produce substances that could irritate the skin or eyes. Although  algae might not present a health risk, it can make the water cloudyand your pool look dirty, thus negatively impacting your pool enjoyment. Your constant chemical cleaning can reduce the amount of algae in the pool. If that does not help, you should contact a professional cleaning service.