How to Get Yellow pH Stains Off a Hot Tub

Drain the hot tub of water. Turn off the pump and any other electrical switches.

Mix two parts diatomaceous earth and one part rust remover in a bucket until it is the consistency of peanut butter. Do not breathe in the powder from the diatomaceous earth as it consists fine, sharp particles that can damage your windpipe and lungs.

Put on latex gloves. Place the mixture on a paper towel or on a spatula and gently spread to a thickness of ½ inch on the area of the stain. Let it rest for up to two days. Remove the mixture carefully by wiping with a damp cloth followed by a clean towel.

Repeat if the stain remains visible. Be sure to dispose of the mixture properly; keep it out of the reach of children or pets.

Test the pH of the water periodically with a pH strip to ensure that no further staining occurs. If the pH level is too high or too low, you will have to add small quantities of certain chemicals to adjust the water concentration.