The pink, slimy growth that is often referred to as “Pink Algae” is technically not an algae but rather a bacterium of the genus Methylobacterium. Pigments within its cells give it its distinctive pink color. The slime formed around the bacteria provides it with a high level of protection which is why it does not brush off easily. In addition to clinging to the walls of a pool, it has an affinity for PVC plastics and will attach itself to both the inside and the outside of PVC materials that are a part of, or attached to, the pool. This includes your pool’s plumbing as well as your cleaner/vacuum. There was a large outbreak of this around here a couple of years ago, late in the season. The most common cause is letting FC get too low for the CYA level - even for a short while.
Because it is a bacterium, algaecides will not prevent or get rid of this. However,
SLAMming the pool with chlorine will. When SLAMming, be sure to clean behind the light fixture, if your pool has one, as well as around any ladders and underneath any removable steps. Treat any pool toys/floats as well with a water/chlorine solution. Since this slime can attach itself to the plumbing (meaning in places you cannot see it), it would be a good idea to maintain your FC on the high side of the target range for a few weeks or so after completing the SLAM process just to be on the safe side.
