CALCIUM BUILDUP ISSUES

[rmklaw]

I am having a calcium buildup (discoloration of 3-year old salt water PebbleTec pool (30,000 Gal) and calcium buildup on the tiles. However, my water chemistry looks fine and can't figure out why this is happening. Chemistry as follows:

Salt: 2900 ppm
Free Chlorine: 3
Total Chlorine: 3.1
PH: 7.3
ALK: 40
CH: 270

Also, my ALK cannot keep up and I am constantly adding ALK UP. Maybe due to the TotalControl Pool Pilot adding maintaining the acid level all the time.

What can cause the calcium buildup and discoloration with low PH and low CH water? Thank you in advance.

 

[mknauss]

Can you post some pictures?

If this is waterline scale, you will get that regardless.

How are you testing your pool water chemistry?

 

[rmklaw]

Thanks for the response. The lighter area show the discoloration from calcium deposits. The equipment used for testing is: K2006C Fas-DPD and also LaMotte Digital. All with brand new chemicals.

 

[mknauss]

Is your CH result from the K2006?

 

[rmklaw]

Both the L2006 and my Digital LaMotte show the same CH. Also, took a sample to a local pool store to test y is roughly the same. I also tested hardness with LAB equipment that I use in a winery. So numbers are accurate. Initially when the pool was redone, CH was high (400) due to the builder overcompensating after the acid wash. We replaced 76% of the water and the CH is stable at 270-280.

I figured that with the low (7.2-7.3 PH) and low ALK, it would eventually dissolve the calcium deposits and stop from accumulating. I am at a loss.

 

[mknauss]

Great. We only rely on the K2006 data. The others are not consistently accurate.

Your water chemistry does not show a scaling tendency. It may be a form of calcium nodules from the plaster.
See Plaster Problems in this wiki article. Plaster Installation and Maintenance - Further Reading