First off...if you've got a pool that's cloudy or green proceed to step one.
Step 1) - Take a breath and go buy a bottle of patience. Clearing your pool can (and will) take some time. But your pool didn't end up in this condition in just one day, so don't expect it to clear up in a day or one weekend. Most times it will take several days to more than a week to clear the pool. The important thing is that you're pool will clear up.
See this thread for first hand pictures of how bleach could clear a bad algae problem, at the poolforum
Step 2) - Some things that will help other troublefreepools members help you. When you post try to include the following...
Your problem:_______________ ever happen before(how often):__________
Have you added something recently to remedy this problem(what/how much):_____________
Include a description of your pool.
size:______ gallons:_____ Above ground or in-ground:_________
Material it's made of:___________ Year it was put in:___________
Include a description of how you normally take care of your pool.
Chlorine, baquacil, SWG, other:___________ type of chlorine used:___________
Are there any chemicals that you use daily or weakly(not mentioned above):_______________
Are there any recurring problems in your pool:__________ how often:____________
What was used to correct the problem:__________________
You need to provide a full set of water test numbers (either from yourself or your pool store)
FC:________ CC:________ TC:_________ Ph:_________ TA:________
CYA (stabilizer):________ Salt (if using SWG):_______
Step 3) - My pool is cloudy, why? There are a few reasons why a pool may be cloudy. Your pool may be cloudy because the Ph has drifted up a little too high. Bringing the Ph back down to the 7.4-7.6 range may clear up the cloudy water. You can use muriatic acid to bring down the Ph. To find out how much muriatic acid you need use The Pool Calculator by JasonLion!.
Another reason you may have cloudy or green water is because you're either on the verge of an algae bloom (cloudy) or right in the middle of a full bloom (green). Either way...Chlorine can and will clean this problem up. You will need to take a deep breath, have alot of patience and a little faith
You should get a decent test kit if you care for your own pool. But if your fighting an algae bloom you really need to get your own drop test kit right away, so don't wait. Get one now! http://www.tftestkits.com/ are a great complete test kit. If you need something right away you can get something that is a FAS-DPD type test kit.
Remember that you still need to provide a full set of numbers (step 2), but during this fight with algae you will be taking chlorine readings as often as you can. The more often the better!
Fighting algae (assuming you have already posted a full set of numbers)
1) Bring your chlorine up to the appropriate "shock level". From now on you want to keep your chlorine level at this "shock level" until your fight is over. Also check your Ph levels throughout this process.
2) Run your pump and scrub the sides of your pool as much as you can. Scrubbing the sides will expose the algae to the chlorine, which will in turn kill the algae. Vacuum vacuum scrub vacuum. You will also need to clean (or back-flush) your filter often during this process (more than once a day may be needed for a bad bloom). Run the filter as long throughout the day and night that you can.
3) Keep a water test log during your fight with the algae. Check (and record) the chlorine levels morning, noon, afternoon and night if at all possible. If you notice that your chlorine has dropped during any of these chlorine checks, add the appropriate amount of chlorine to bring you up to your "shock level" again. Chlorine is what will kill the algae so it will get used up very quickly at first. Checking and keeping the chlorine levels high is what will speed the fight against algae. Your persistence here is the key! FIGHT FIGHT FIGHT!
4) Stick with it! Check your chlorine levels...add chlorine. Check your chlorine levels...add chlorine. Scrub, filter, clean the filter. Check your chlorine levels...add chlorine. You get the idea. Remember that this is going to take a good while. Stay the course and stay persistent! You will not clear your problem in a weakend...what you want to do is totally eradicate this problem. You don't want this problem coming back throughout the year. Stick with it and fight! Check your chlorine levels and add chlorine. Scrub, vacuum, filter filter
5) Continue with step 4 (above) until your evening chlorine level hold overnight into the next morning. When the chlorine level holds over night then your fight is near an end. Continue to check your chlorine levels another 24 hours and add chlorine during the day if needed. See if your chlorine holds overnight a second night into the next morning. Do not move on to step 6 until step 5 is complete.
6) How does the water look? If it is clear you now need to get on a good maintenance program which will set aside a minimal amount of time each day so another algae bloom doesn't strike. For most people their pools will clear if they stick with the program. If your pool problems are solved, go enjoy your pool! But if your water is still dirty, green or cloudy...take a breath. It can still be fixed. Get a new set of complete numbers and post your situation, your previous and current numbers and the chlorine/Ph reading during your fight with the algae.
Fight Fight Fight!