Even with good maintenance and preparation, after a prolonged rain shower your pool water may be overwhelmed with algae and turn green. Here are simple ways to clear that up.
First we should get over to our local pool supply store and pickup the correct amount of shock and chlorination tablets. The shock will overload the pool with chemicals to clear up and kill the algae. 1lb shock packages can go for $3 - $7 or more depending. Even the cheaper ones will do the job if measured and applied correctly.
Pour this into your pool or add to the skimmer as per the instructions. With the chlorination tablets do not throw them into the pool directly. it can discolor and possibly further damage the lining of those with above ground pools.
In a matter of hours you will see a clear difference.
Since the shock process will take time, especially if your pool has turned a dark green, we should make sure the rest of our filtration system is working well.
This would be a good time to clear the skimmer and the pump filter. The actual water filter should be cleaned after the algae or green pool water has been cleared up. Unless of course the pool is not only green colored, but with tactile green sludge algae already coming from your water inlet.
Overnight the pool will have cleared up if done properly and you'll be able to see the sediment at the bottom of your pool, if any. Using your available tools, clear this up.
Now is the time to disassemble your water filter and clean or replace the element/s. This will assure that your filter is running optimal. You CAN clean the filter before and after should you wish.