above the water mark is pristine below is a different matter. I have a grey scale substance built up and have tried scrubbing and it still doesnt come off. We have a septic tank so I have to be careful about what I use. Any suggestions?
My sister told me you need to take the water out......but don't syphon it- gloves on, and scoop out water with a container. That way product (which ever you choose) won't be diluted, and will work more efectively.