Calcium hardness

[Smachado]

Recently the calcium hardness in my pool increased to over 400ppm. Following instructions from leslies pool employee I drained the pool and then refilled. While it was filling I had our tap water tested which showed calcium hardness of 38ppm. Tested the new water before adding any chemicals- all readings were nearly zero. I then began adding chemicals per leslies instructions . One week later the calcium hardness rose to 361, one week later to 386 and today its 409ppm. Draining did no good. Currently using Clorox pool & spa ultra blue chlorine tablets and leslies power powder plus shock, later trying to eliminate algae. Help!!

 

[Stuamurr]

Tablets and Granules will increase your CH but shouldn't be going up that fast even with shocking, given you've got low CH in your tap water this should keep your CH in check due to dilution. I think you need to head over to pool school as it sounds as if you have been 'pool stored' in order to gain independence in testing and maintaining your pool.

In the meantime could you please provide further details, full test results, pool information and chemicals your 'friendly' pool store employee lead you into buying and using - a who what when where and why if you like.

 

[peterl1365]

I've had CH of 500+ in my pool ever since it was built 13 years ago. I don't think it has caused any issues other than minor waterline scaling. I've done partial drains a couple of times when it got over 1000, but I don't think I've ever gotten it below 400. My fill water is probably around 100 ppm so the minerals accumulate with time.

One thing to remember is that CH is not only because of fill water. Depending on your pool surface, a significant amount of solids can be leeached out of the plaster (if that's what you have). Replacing with "hungry" 38 ppm water may just cause more minerals to get pulled out of the plaster until it reaches an equilibrium.

While true that too much hardness can cause scaling, I suspect that constantly chasing the recommended hardness levels (100-200, IIRC) might also accelerate the rate at which your pool surface wears out.

Nota bene: I'm definitely not an expert on this. Just my musings on very basic chemistry concepts.