The calcium hydochlorite will not dissolve in our pool.

by Patrice
(Raleigh, NC)

The calcium hydochlorite will not dissolve in our pool. It is suspended in the water and clings to the tile line in our gunite pool.

Ph is at 7.5 Everything else is balanced. We had it re-surfaced 2 years ago with a small pebble like plaster product. It is a 100,000 gallon pool. (yes, you read that correctly!) Any suggestions how to dissolve it? The tile line is unsightly!

Hi Patrice. First thing is to stop using calcium hypochlorite. It's sold as "shock". Liquid chlorine or unscented bleach will handle 99% of your chlorine needs, without the side-effects of cal hypo. Just remember to sweep after each gallon is added.

The operative word is calcium, which is a hardened metal, and can be difficult to dissolve in water.

You can turn the pump motor off, allow everything to settle to the bottom, then vacuum to waste or filter. If you choose filter, you're going to need to backwash a couple of times.

If waste, make sure the water level is kept topped off.

You have a larger pool so it may take some time and grunt work to accomplish this. In the meantime, you can maintain a lower pH of 7.2 - 7.4. This keeps the water a bit more on the acidic side to lessen the affects of calcium rings at the water line.

The TA is closely tied to the pH, so make sure it's in range of 80- 120 ppm.

There's no chemical that you can add to force the water to accept the cal hypo. What you're getting into with this statement is the Saturation Index. There's a wheel that is included with the Taylor K-2006 pool water test kit that measures the SI.

Some people choose the Calcite Saturation Index as a more accurate measurement.

If the calcium rings at the water line are getting out of control, maintain a lower pH as stated above. And you can also use a pumice stone to scrape away any excess calcium. 220 grit sand paper works as well. There's also a product called Gysar Tile Brite that you mix with a little muriatic acid. It forms a goopy mixture that you apply to the tiles and eats away the calcium.

Hope this helps and have a great Summer.


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Jul 15, 2017
Cal-Hypo is loose, not hardened on tile
by: APatrice

Thank you for your thorough report. However, the calc hypo is SUSPENDED in the water. And the calcium hypo is not hardened on the tile -- it is free forming against the tile in little granules. (and yes, we do have several tiles that have that hardened, seeping calcium on the tiles) We'll try your suggestion for that problem.

What do we do about all the suspended calc hypo that won't dissolve or dissenegrate?

Once something is in the pool, it's in. There are a few things you can do. First is to keep filtering and backwash every couple days. Sweep the pool a couple times per day to keep the particles suspended in the water.

Next is to turn the pump motor off and allow everything to settle to the bottom, then vacuum to waste. Make sure to keep the water topped off. A fine mesh leaf rake will also help. You can manually scoop out the floating particles.

Last is to do a partial drain and refill. Unfortunately there's chemical to simply get rid of solid objects in pool water.

And stop using cal hypo. No reason to ever use it.


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