Poolcleanining
Hello,
I’ve owned this pool for two years, and before each season I run into the same problem: a layer of residue builds up on the bottom of the liner. I’m not sure what it is — possibly some kind of biofilm, organic residue, or metal-related buildup.
The same material also sticks to the pool walls, mainly around the water inlet, although it isn't as much/strong buildup there.
The chlorine, alkalinity, and pH levels are all within normal ranges, and in my opinion the circulation is good. I backwash the filter weekly (if that’s any indication of proper flow). A robot pool cleaner, a vacuum connected to the inlet, and scrubbing with a regular pool brush do not remove the worst of it (see picture). The pool brush does remove most of the buildup on the walls, though. What actually works on the floor and stubborn areas of the walls is a stiffer household scrubbing brush.
The pool water comes from the same supply as our tap water, which contains a relatively high amount of calcium/limescale.
My current theories are:
- Poor circulation or dead spots in the pool
- The liner surface is worn out and trapping dirt easily (the liner is around 12 years old and welded)
- Some kind of contamination coming from the pool cover
- The thuja hedges around the pool are affecting the water quality
- The left side of the pool floor gets more sunlight than the right side, increasing the growth of whatever this is — although that doesn’t explain the buildup on the walls
- The water itself may simply be old and need replacing, although it was changed the year before I moved into the house
I even had a pool technician come by, and he said he had never seen anything like this before. Any help or ideas would be greatly appreciated.
One more thing: the pool has continuous circulation — lower flow at night, but normal flow during the day.