Cause of calcium/scale buildup on perimeter tile.

[poolaris]

I have a tremendous amount of white deposit on my tiles and suspect it is caused by the Salt water chlorine device as it produces enough calcium buildup on the cell plates to bridge the plates completely unless it is cleaned every day. My chemistry numbers are as follows.
CL = 5.5 CC= 0, PH =7.6, TA =70, CYA =60, Calcium Hardness =900-1000, Salt = 4200
I refilled the pool 20 months ago and the CA then was 200. If the high CA is not caused by the SWG what other things can be causing it?

[nefretrameses]

What is your source of chlorine? Cal-hypo? How are you testing?

[kelemvor]

The SWCG causes bubbles in the water during operation. This aerates the water, and drives pH up. That, combined with your very high calcium are producing the scaling.

I can't say where the calcium came from, but it's not produced by the swcg.

There are some instructions for reducing the calcium levels here: http://www.poolforum.com/pf2/showthread.php?16992-Lime-Softening-to-Reduce-Excess-Hardness-Bucket-Test-amp-Treatment-Process

In the meantime you can reduce the scaling that gets produced by the swcg if you keep your pH levels a little lower. 7.2 or 7.4 maybe.

[Poolsean]

Where are you located? If you're in a dry area and tend to lose water from evaporation, when you add more water to top off the pool, you're adding more calcium into the water. The calcium does not evaporate with water and will continue to build up over time. Are you superchlorinating your pool on a periodic basis? If so, what are you shocking with? If it is a calcium hypochlorite product, that will contribute to the increase in calcium hardness also.

The salt system should be designed with a self cleaning feature built in, but if it shows signs of scale, your water chemistry balance is out of balance. As mentioned, lowering your pH will help. However, if you have excessive scale formation on your tiles, you will need to ensure you maintain a lower pH (some may call it an acid bath) for a few days to dissolve the calcium. There are some calcium remover solutions that require some elbow grease to get the calcium off. In some extreme cases, I've heard of needing a chisel to get it off, but is not usually recommended. You can damage your tile!

[CarlD]

Poolsean knows. He's been very helpful with me and my first year with an SWCG.

But the extremely high calcium isn't good for any pool. Were your T/A to go up to say, 200 (maybe even as low as 150), you could expect immediately for your pool to go milky white. With vinyl pools and reasonable T/A I normally say don't worry about CH, but yours is excessive and is already causing problems.

[poolaris]

Where are you located? If you're in a dry area and tend to lose water from evaporation, when you add more water to top off the pool, you're adding more calcium into the water. The calcium does not evaporate with water and will continue to build up over time. Are you superchlorinating your pool on a periodic basis? If so, what are you shocking with? If it is a calcium hypochlorite product, that will contribute to the increase in calcium hardness also.

The salt system should be designed with a self cleaning feature built in, but if it shows signs of scale, your water chemistry balance is out of balance. As mentioned, lowering your pH will help. However, if you have excessive scale formation on your tiles, you will need to ensure you maintain a lower pH (some may call it an acid bath) for a few days to dissolve the calcium. There are some calcium remover solutions that require some elbow grease to get the calcium off. In some extreme cases, I've heard of needing a chisel to get it off, but is not usually recommended. You can damage your tile!

I am located in a desert area East of Phoenix, Arizona. I have only superchlorinated the pool once since iot was filled only because we had a dust storm which deposited a lot of leaves in the pool. I used 4 x1 gall bottles of 10% liquid sodium hypochlorite chlorine, but I really don't think that caused the problem as I had the scaling before. High ph has always been an issue which I struggle to control. A while back I tried removing the calcium with a pumice stone which wore out to nothing when scrubbing just one 6" piece of tile and it made no difference. The salt system is anything but self cleaning and needs cleaning twice daily in the summer to prevent the cells bridging, so since May I have had it switched off as it was less work to add liquid chlorine on a daily basis. I test the ph and Cl levels twice daily with a Taylor K2006 dpd kit, but TA is only tested every two weeks.

I just saw a neighbor's pool which was green with algae, where they had run the pump 1 hr daily and NEVER tested their water EVER, the water was crud but the tiles surrounding had no scale whatever, but they did not have a swg system but then they seldom added chlorine. I check my pool out twice a day and the water is always sparkling and yet my tiles look like crap. Yes, I did try chipping some of it of with a sharp woodworking chisel and also a grinding wheel but it still did not budge!