Used this and it worked great. I also had some rust stains from my rod iron chairs on the concrete and I poured the cleaner into a plastic bowl and poured it on the stains and let it sit for a minute and hosed it off and stains gone. That's called a 2 for one.
Excellent Filtration: This 50 Sq. Ft. filter is known for its fine particle filtration, helping keep your hot tub water crystal clear. It does a great job capturing dirt, oils, and debris.