What Does Scale Look Like?

[Gavin]

I have a high CH reading.

[Mark]

I have a high CH reading.

Not much to go on. What type of surface are you talking about? If you have white plaster, scale is difficult to see but usually you can feel it as a rough surface. With colored plaster, you can usually see it as discoloration of the plaster but that too can be caused by other things.

High CH is not by itself cause for scale but it does make it more likely. CSI is a better indicator of scale. I end up with CH well over 600 ppm by the end of the season but keep scale at bay by keeping PH and TA at the lower ends of the range.

[Gavin]

I have a high CH reading.

Not much to go on. What type of surface are you talking about? If you have white plaster, scale is difficult to see but usually you can feel it as a rough surface. With colored plaster, you can usually see it as discoloration of the plaster but that too can be caused by other things.

High CH is not by itself cause for scale but it does make it more likely. CSI is a better indicator of scale. I end up with CH well over 600 ppm by the end of the season but keep scale at bay by keeping PH and TA at the lower ends of the range.

Thanks Mark for the reply. I'm looking after a friends pool for him while he's away and was doing some testing and found his CH was 1700! I replaced some water and got it down to 1200. pH was 8.0 so I added some acid to drop it to 7.6. TA was 140 and it dropped to 120.