Just joined as new member. Found the website when dealing with some nasty algae problem in my pool. Actually I built the pool around 6 years ago and since I never had any algae problem. My pool is located in the Philippines, a bit outside of Manila. It's about 9m x 4.5m, no so big but fine for us, especially the kids enjoy most of it. Also it's not so deep, as we considered for the kids, the deepest point is about 1.5m (5 feet). The filing requires 54,000l or about 15,000 gallons. Actually since the first fill up, the water was never drained, since 6 years the water renewal is just through filling up the evaporated part. The daily fill up can be quite some, depending on wind speed and temperature.
For the sudden algae attack, I "blame" the endless rain during the past weeks. Seems that a lot of spores came into the pool and found a good breading ground. It took me two days with intensive chlorine shock and keeping pH at level. Now it's "blue sea" again. My supply shop recommended some algeacide (copper based) to prevent from happening again. I will try and see whether it helps because I am not a "friend" of high chlorine level in the pool, especially as the kids are using it.