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What Is Mineral Control?


ulao

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A recent pool test is calling for mineral control. The calcium is apparently high in my pool? Most of the time these "special" fixers are simply one main ingredient wrapped around a pretty bottle with a fancy name on it. I tried to do some research but I'm not finding anything. What is the best way to get the calcium down?

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You really should get your own proper test kit so you can manage your pool yourself and not be at the mercy of the pool stores. Get the Taylor K-2006 test kit. Then do a full set of test results and put them into PoolMath. If your Calcite Saturation Index (CSI) isn't high such as +0.6 or above, then don't worry about lowering your Calcium Hardness (CH) level.

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What gave you the impression I don't use a test kit? I use a taylor kit that was recommended on here (looks like the picture you linked) . I can certainly do my own test but we take it in to the pool store every now and then just to make sure we are testing things right. Either way I know it is high and ill do a test when I can but I just picked up the recommended bottle at home depot as I didnt get a quicker reply.

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I'm sorry I made a bad assumption. You're statement "A recent pool test is calling for mineral control" had me think you went to a pool store for testing and that they tried to sell you a product. Sounds like I was half-right (i.e. the pool store did test and recommend, but you have your own good test kit).

Anyway, post your results and then we can tell you if you really need to add anything. Also post exactly what product they had you get (brand name and, if listed, the ingredients).

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That number makes no sense at all so yes, check with the kit by measuring pH, TA, CYA, CH, and temperature (and salt level if it's high; otherwise setting 0 will use the minimum implied by the TA and CH you enter into PoolMath).

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No, "mineral water control" means controlling the level of minerals in the water. The minerals can be calcium which should not get too high or else one can get calcium carbonate scaling, or the minerals could be metal ions such as iron or copper which should not get too high or else they can stain plaster surfaces.

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So using PoolMath and using a water temperature of 85ºF (you didn't give the temperature of your pool water), your Calcite Saturation Index (CSI) is -0.13 which is OK. Yes, the TA could be raised some but not too much since TA is a source of rising pH since higher TA outgases carbon dioxide more quickly. Given your high CH, I would keep your TA lower at 60 or 70 ppm. To add 10 ppm TA, you would add 23 ounces weight or 19 fluid ounces volume of baking soda.

When you did the CH test (and other drop-based tests) did the titrant drops come out well-formed and not squirt out? Static electricity can build up and cause drops to not be large enough in the test (usually this is seen in the TA test).

What kind of chlorine are you using? It's unusual for your TA to be that low unless you were adding acid or using a net acidic source of chlorine such as Trichlor tabs, but with Trichlor your CYA level would build up higher.

The only reason you would use a scale prevention product would be if you were unable to maintain the lower TA and keeping the pH in line. Since it looks like you don't have a problem with that, you don't need such a product.

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85 was a great guess ;)

Yes my drops are very drop like, never knew that, interesting thx. Now sure why you asked about chlorine? I have a SW pool ("My pool is SW 10,000 gal.") and normally just add salt unless I need to sock the pool. My TA is not normally like this and was at 70 before I added the mineral control, is that possibly what brought it down? We use stabilizer to keep the TA from bouncing around.

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Oh, I missed the "SW" as meaning a saltwater chlorine generator pool. Yes, you'll want to keep the TA lower in such a pool anyway since the pH tends to rise in such pools. You can use 50 ppm Borates in the water (added most easily from boric acid) as an additional pH buffer if the pH rises too quickly for you.

I don't think the mineral control would affect the TA. It should only affect the CH though I'm not sure if the CH test will measure the calcium bound to the sequestrant or not -- depends on the relative bonding strength of the sequestrant, the Calcon indicator dye, and the EDTA titration drops.

As for stabilizer by which I think you mean Cyanuric Acid (CYA), that does somewhat buffer pH as well but it mostly moderates chlorine's strength and prevents it from getting as broken down by the UV in sunlight. If your pool gets a lot of sun then I'd suggest raising the CYA towards 80 ppm and keep a minimum FC of no lower than 4 ppm in that case though you are already at a higher FC level for your CYA level. The minimum for an SWCG pool is an FC that is no lower than 5% of the CYA level.

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No, "mineral water control" means controlling the level of minerals in the water. The minerals can be calcium which should not get too high or else one can get calcium carbonate scaling, or the minerals could be metal ions such as iron or copper which should not get too high or else they can stain plaster surfaces.

 

So what is the normal Mineral water control for spa?

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You don't need to use mineral water control or any other metal sequestrant or anti-scale product unless you actually have a problem with your water chemistry such as water that is high in iron or copper -- say more than 0.3 ppm of either. For anti-scale, Calcium Hardness (CH) that was above 200 or 300 ppm in a spa might need this product, though depends on other parameters such as Total Alkalinity (TA) and pH and temperature. You can use PoolMath to enter water chemistry parameters and it will calculate the Calcite Saturation Index (CSI) that will tell you if you water is at the risk of scaling. For a spa, the CSI should not be higher than +0.3 though 0.0 or below would be better. A negative CSI is OK in a spa that does not have plaster or grout exposed to water (most spas are acrylic).

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