Calcium Hardness and Vinyl Pool

Total hardness and calcium hardness in pool water.
Scale, calcium buildup, hard water and scaling problems.

Calcium Hardness and Vinyl Pool

Postby Womble- » Fri 21 Mar, 2008 23:48

Hi I have a Vinyl Pool, I read that Calcium Hardness is not that important for Vinyl Pools.

My CH tested today was 90.

I have read that the CH should be between 200 and 400 but that it does not matter for Vinyl Pools. So I am guessing it is the pump etc that would be of concern to a low CH.

Does low CH cause cloudy water? I have slighty cloudy water but I have a feeling that is a hang over of not managing the pool for a week. I did a full test this morning and upped all my levels and now have the following (6 Hrs after adding chemicals)

FC 8
TA 110
CYA 40
PH 7.3 (ish)
CH 90


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Postby chem geek » Sat 22 Mar, 2008 02:53

Low CH will not cause cloudy water. Only very high CH (or TA or pH) can cause cloudiness and scaling. Low CH is not a problem for a vinyl pool. The CH is needed for plaster or any exposed grout (for tile) that may be touching the water. If there's none of that, then the water is fine. As for pumps and other metal surfaces, low pH is the primary factor for corrosion along with high oxidizer level (so FC/CYA ratio) and high conductivity (TDS), but at normal values for an outdoor pool, metal corrosion is minimal.

So unless you've got some exposed grout or plaster, don't worry about the CH. Your current level is fine. If you want to add more, you can without a problem, but it isn't necessary.

As for your cloudy water, it may have been an algae bloom starting since you said you weren't managing the water for a while so I suspect the chlorine level got too low. Just keep the chlorine level up. If you want to shock the pool to make the algae (if that's what it is) go away faster, then you can raise the FC to 40% of the CYA level, or 16 ppm in your case. Or you can just keep it at 8 and take longer, but most important is to test and add more chlorine if the FC drops since it will likely get used up killing the algae. Also, be sure to run the pump and see if the filter needs cleaning. Brushing the walls (carefully, since it's vinyl) also helps.

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Re: Calcium Hardness and Vinyl Pool

Postby dougbryant » Mon 24 Dec, 2018 15:47

cloudy water i noticed post that good readings but combined chlorine reading was ommited if too high the presence of chloramines ie dead algea spent chlorine etc could well cause cloudiness and also the characteristic stinging eyes

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