Several factors can contribute to foaming in pools:
- Soft water; low calcium hardness levels
- High TDS levels
- Lotions, oils and animal fats in the water
- Poor water balance
- Low grade algaecides. 10% polymers.
- Tile cleaning phosphates
- Use of aeration (air jets) in biguanide treated pools
Correcting the above conditions can reduce or eliminate foaming. Anti-foaming agents are widely available at pool supply stores and online.
Chitin products like Sea-Klear can prevent or eliminate foaming from occurring. The Natural Chemistry line of enzyme products are also very effective antifoam agents. Sometimes balancing the water and shocking the pool can remove the foaming.