High Calcium Hardness & Pool Alkalinity...

by Diane

My test kit came via Endless Pools, but I believe it is the one offered at this website.

It looks exactly the same, is made by Taylor i-CARE (K-1005). My pool has become unbalanced and I am trying to sort things out so I don't have to discard the water (in this desert) and start over.

The history:

Total chlorine suddenly became very high, relative to free. After I added chlorine, the pH went sky high, and I have had difficulty stabilizing it since then. Calcium hardness was too low, so I added increaser and now it is very high (600), though the distinction between red and blue was quite subtle (changed just gradually).

A white deposit has occasionally precipitated at the pool bottom. In testing for total alkalinity, it says to add 2 drops of R-0007, and then 5 drops of R-0008. The sample should turn green, and then R-0009 should be added drop-wise until the solution turns red.

However, after the first two steps, the solution is not green, rather the color of very dilute urine. I don't know what to do to make the green appear. Is the alkalinity too low or too high? Is there something wrong with my test chemicals, or is there some other problem? Would it be better to drain the pool and start over at this point?

Thanks for the questions Diane

Your question says that the chlorine went high, so I will assume that you either added too much by accident or shocked the pool. The pH would only go up that high if you used Calcium Hypo. granules. Or if you have very high pH fill water.

I always tell people who live the the southwest or other places that have hard water to use either grocery store bleach or liquid chlorine.

Chlorine granules normally have a pH of about 12 and will increase both the pH level and calcium level. I took care of hundreds of pools in Mesa, Phoenix, and Tempe for years so I'm very familiar with the kind of water you have.

If you need to use the pool you can get a chlorine neutralizer called Thiosulfate. But only use this if you absolutely have to, such as a pool party. It does tend to mess up the water if not properly added. Get your chlorine level between 1.5 - 3.5ppm. The sun should help get the level down. Thiosulfate is the R-0007.

You want to get the stabilizer (cyanuric acid CYA) to between 30 - 50ppm. Your K-1005 kit should have a test for that. Use Trichlor to increase the CYA. If there's too much the only way to reduce it is to drain 1/3 - 1/2 of the water and refill. Chlorine tabs already have CYA in them.

You want to test the CYA weekly to ensure it says at the correct level. Be very careful in adding any calcium to the pool. It should be kept between 150 - 250ppm. Test the tap water so you know what your starting point is. This is mostly for plaster pools.

Your tap water might be high anyway so there's no need to add any calcium. The only way to get this down is to drain 1/3 - 1/2 then refill, similar to the CYA. The white deposit on the bottom of the pool is probably the calcium settling.

You can vacuum to WASTE (DE and sand filters) then refill with fresh water. Be careful to keep the water level above the skimmer. If you don't the system will draw in air. It is possible that the Reagents are bad. There's a trick you can do, but you need to be careful in getting the right amount of pool water.

Fill the large vial just a hair over the 10ML mark with pool water, about 12ML. Fill it up to the 25ML with tap water. The sample water is now diluted by 1/2. Swirl to mix. Then add the Reagents as normal for the alkalinity test.

If the reading comes out normal you know the alkalinity is too high and there's nothing wrong with the Reagents. Just multiply by 2 and that will be your alkalinity reading. If this is the case you need to get the alkalinity down. Go to these links to do that:

Pool Alkalinity

Total Alkalinity

You can also test the alkalinity of your tap water. This will also indicate if the Reagents are bad. If they are bad you'll obviously need to replace them with fresh ones. Take a sample of water in for testing if you have a local pool store. They should be able to do that for free. When adding Reagents be sure to swirl between each dropper application. Don't add the 0007 then the 0008 without swirling.

It will give you a bad reading. You may not need to drain all the water but if the CYA and/or calcium is way too high you might need to drain 1/3 - 1/2. These links can also give you alot of information. It's everything I learned taking care of pools in Arizona and being the pool operator at our YMCA for the last 3 years.

Swimming Pool Chlorine

Pool Tips

Calcium Hardness

Water Testing Kit

Hope this helps and let me know how it turns out for you. Best of luck.


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