ph- A measure of acidity or basicity in your water, from a scale of 0-14, 7 is neutral. ppm- Measurements of any chemicals concentration, parts per million. acid- chemical that lowers ph level. algae- Microscopic organisms that enter your pool from swimmers and dust. This causes cloudy water. chlorine- Sanitizing agent that kills algae and bacteria in your pool. shock- Oxidizer to destroy chloramines and other undesirable components such as suntan oils, prespiration and urine. Cloudy water is a good way to tell that pool levels have changed. Treatments for your pool can be in the following steps, 1. Balance, 2. Chlorinate, 3. Shock, 4. Algaecide 
Several test kits are available at http://www.walmart.com/search/search-ng.do?search_query=pool+test+kit Poolmaster Basic Four Delux - With case, tests for chlorine, bromina, ph and acid. Test strips test for chlorine, bromine, alkalinity and hardness. Also if your pool is cloudy, aqua chemhas an envirnmentally safe clarifier that clears cloudy water.
Total alkalinity refers to all of the alkali soluble salts in the water ( in ppm- parts per million parts of water by weight. ) You can bring the ph down if your pool's alkalinity is over 100 ppm and the ph is over 7.8 by adding more acid, doing so by putting in a little at a time to bring the ph down to 7.4. Use rubber gloves when applying algaecide, the amount depends on the amount of gallons your pool holds. You can buy one that treats several types of algae or one specific for a certain algae such as copper- based that treat yellow algae. When applying, make sure the pool is running to circulate the algaecide. After 24 hours vacuum the pool to remove dead algae debris. 
