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Ph Balance


ed3120

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I don't understand how to use Leisure Time's PH Balance product. It says to not add it to water that has more than 150 ppm calcium, but I always see recommended spa calcium levels to be 150 to 400 ppm.
So if you use it in water with calcium above 150 ppm, the water gets cloudy.
If you keep your calcium below 150 ppm, it's bad for your spa.
Why would anyone use this product?
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The product is a phosphate buffer, but will precipitate calcium as calcium phosphate which is why they recommend lower calcium.

The recommended spa calcium levels you are talking about are wrong. With Calcium Hardness that high -- especially 300 ppm or more at hot spa temperatures and with pH that may be high, you can get scaling in the spa, especially in the gas heater.

If your pH tends to rise too much, then you can prevent that by keeping the Total Alkalinity (TA) lower -- for hypochlorite sources of chlorine have the TA as low as 50 ppm. Use 50 ppm borates as an alternate pH buffer that doesn't have the side effects of pH rise from TA nor calcium phosphate precipitation from a phosphate buffer.

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I would keep it below 150 ppm to prevent scaling. It's OK to keep it around 100 ppm if you prefer. The higher CH tends to reduce foaming, but if foaming is not an issue in your spa then a lower CH is fine. This assumes that you don't have a plaster spa or grout between tile exposed to water.

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Oh, so is the standard 150 ppm - 250 ppm Calcium recommendation is just to keep foaming down? I'm not that worried about foaming...more worried about not causing damage to the spa. What would be the minimum Calcium recommendation to prevent damage to the spa? My spa is 5 years old and has an acrylic shell.

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Acrylic shells do not need any calcium in the water. There is a lot of misinformation in the industry that keeps getting repeated. Plaster spas need calcium to prevent the surface from being damaged Stand alone acrylic spas do not. Higher calcium levels do not protect against metal corrosion. Period! This is all because the swimming pool industry adopted the Langelier Saturation Index (LSI), which is useful for closed system like boilers to predict scale formation in pipes but not applicable to open systems like pools and spas. Calcium Saturation Index (CSI) is more useful but only for plaster and aggregate finish pools and spas to keep the plaster from dissolving and causing surface damage and for some fiberglass pools to help prevent metal staining and cobalt spotting but vinyl pools and acrylic spas do NOT need calcium in the water. 100-120 ppm is fine and is high enough to minimize foaming. Completely soft water will foam more readily than water with some hardness.

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Thank you for the information. It's surprising since I've read so many things saying the opposite. I thought it could hurt the heater pipes or something. (I'm not saying you are wrong...I just don't understand why there is so much misinformation out there.)

"Water that is low in calcium hardness can be corrosive to other metal parts in your spa, particularly your heater. We recommend maintaining a calcium hardness level of 150 - 400 ppm." Leisure Time http://www.leisuretimespa.com/SpaFAQs.asp?authID=0#n

" If the water does not have enough calcium, the water will draw from other minerals, including copper, aluminum and iron, (e.g., heating elements, pump seals, and internal parts on gas fired heaters)." http://www.spacare.com/understandingspaandhottubwaterchemistry.aspx

"The ideal calcium hardness level for hot tubs and spas is 200-400 PPM. If your level is below about 150 PPM, some erosion of equipment parts can occur."

http://www.rhtubs.com/info/water.htm

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There is so much misinformation that has been ingrained into the pool/spa industry that goes contrary to basic chemistry. The list of siuch information goes on and on but two at the top of the list are about calcium and "slugging" acid to lower TA/ "walking" acid to lower pH. Believe whomever you want but check the chemistry involved first. The LSI is only a predictor of calcium scale desposit and is not a reliable predictor of metal corrosion at all. Just ask anyone in the boiler industry! That is why there are other (more complex) scales to predict metal corrosion and calcium ion concentration is not the major factor in these.

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Read this thread where the true experts talk about the LSI and metal corrosion. In theory, if one is able to produce a thin layer of calcium carbonate on metal surfaces then they can be protected, but that is completely impractical in situations where water flow, temperature and other parameters are changing. As the thread describes, low pH is a much bigger factor as are the presence of oxidizers. Stainless steel is affected by chloride levels that interfere with the reformation of the passivity layer.

My tap water, by the way, has the following characteristics:

TDS: 136 ppm

Temp: 67ºF

CH: 55 ppm

CYA: 0 ppm

TA: 80 ppm

pH: 7.7

LSI: -0.67

So clearly my water district and in fact most water districts across the country do not saturate the water with calcium carbonate. To do so would make most tap water very hard. Now these water districts do tend to add some corrosion inhibitors and my tap water has around 400 ppb phosphates for that purpose. However, this is to protect copper plumbing for 50+ years in spite of having water that is chlorinated to 1 ppm FC with no CYA so about 10 times higher in active strength compared to pools with CYA. More recently, the water district has switched to using monochloramine which is a weaker oxidizer, but all of these chemicals are selective so it actually attacks certain types of rubber seals in toilets compared to chlorine.

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