Cleaning gunite pools - acid vs. liquid chlorine

[Tmaragni]

I run two gunite pools at the gym I work at and I am planning on draining and cleaning them at the beginning of August. Last year when we drained them, we did muriatic acid wash for each pool. However, my general manager says that at the last place he worked (which also has gunite pools) they cleaned the pools with liquid chlorine and only used muriatic acid on the stains that did not come off with chlorine. Any advice on which method is preferable?

 

[Guest]

IF the stains are organic chlorine will work, it they are metal (scale is a metal stain since calcium is a metal) you need to acid wash which removes a layer of plaster. If you have metal stains then there are water balance issues that also need to be addressed.

 

[Tmaragni]

Thanks for the advice! I have rust colored spots on the bottom of my pool that are definitely some sort of metal stains so I will definitely be doing an acid wash. I keep my pools within +/- 0.3 on the Saturation Index so I wonder if I need to look into a metal sequestering chemical to prevent stains.