The darned thing actually works!Back story -- we live in West Texas where the dust blows. I had a pool cleaning robot but that "died" this winter, complicating things was fracturing my right shoulder during a ski trip (I like to say I swerved to avoid a pregnant nun but the TRUE story is much less "heroic" -- I slipped in the condo). Consequently the pool didn't get cleaned until spring. By then there was "dirt" which couldn't be removed. An internet search convinced me that it was "dirt scale" -- dirt covered by a calcium deposit.The pool looked horrible despite the water being fine. I put in some scale remover but the bottle said that might take weeks or even months to work. Well, the family gets together from around Texas for Independence Day so I decided to give this thing a try.At first I couldn't get the siphon effect working. I emailed the company and had a reply -- within TWO HOURS -- from a Vice President giving me some hints.One thing, which I thought of on my own, was to "inject" water into the tubing using an old turkey injector syringe that I had. That worked like a charm!So far I have done a quarter of the pool each day for two days (hey, its gotten in the high 90's the last few days and I am 70 so I quit in the early afternoon). Both my 11 year old grandson and my (unnamed year old) wife said the pool looks noticeably better. Not as good as it used to but much better. I used a gallon of acid each time. Yesterday the pool pH dropped to 6.4 (although the company says that one may not even notice a change). I put in some pH increaser and withing two hours the pH was back up to 7.4. I'll be working on the rest of the pool over the next few days but I am quite pleased in how this has worked. Even if not looking perfect the pool looks better and I can wait and see what the scale remover does. At worst I can go back later and redo some of the heaviest spots.