Zap-it Shock versus Super Shock-it

I am looking for input from retailers out there selling 1# bags of granulated cal-hypo.  Some companies sell Zap-it and others sell Pool Corp's Super Shock-it while others sell something completely different. What is your feedback on the quality of these products?  I heard that Super-Shock-it was double grinded making it dissolve quicker than other brands but not sure if this is all hype as I can't find anything stating that.  For fast dissolving shock I always recommended dichlor or lithium based shocks but wanted to know what was the opinion of others on these cal hypos.

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  • Check and see if your distributor has anything stronger than the 68% shock. I have a customer in Charleston who was also buying his 73% shock from Leslie's but was paying thru the nose even with his "commercial discount" because he liked the product. Once I sharpened the price on a 100lb drum of 68% cal hypo, he stopped buying it from Leslie's because of such a high cost and started using my shock. Did you buy it from a Leslie's store or their commercial distribution center?

    Luke Norris said:
    I bought some of Leslie's 73% shock today.  It wasn't extra ground at all.  It seemed to do better for me than 65%.  I think I'll be buying more!

  • Hey Scott I have used that Super Shock IT, it has been 3 or 4 years but it is probally the best 68% shock I have ever seen.  I really did like it, but the company took a big price jump and that why I switched back to the arch shock.  

    is the link for it


    I have used that power shock from arch which is 78% and I have never had a problem with it floating to the top.

    Scott Tarr said:

    The customer I spoke with said that the Super Shock-it was 68% but that it was double grinded and I had never heard of that before. He claimed that it was much finer and therefore would dissolve quicker than other 68% cal hypo.
  • We sell mostly cal hypo in our market which is heavily dominated by vinyl lined pools and pre-dissolving is a must in my opinion. In Florida, we would only sell dichlor to vinyl customers as we were always worried that a homeowner might not follow directions and broadcast the product without mixing in a bucket of water. Dichlor was common protocol.
  • The true cost of chlorine sources needs to account for the pH adjustment products that are also required.  Hypochlorite sources of chlorine are all somewhat close to pH neutral when accounting for chlorine usage/consumption which is acidic.  So only a small amount of acid is required for such products.  However, for Dichlor and Trichlor, additional pH and TA adjustment is required since these are both net acidic when accounting for chlorine usage/consumption.


    In this post, I compared the costs a while back accounting for such extra required chemicals using the least expensive sources for consumers.  Chlorinating liquid and Cal-Hypo were roughly the same cost, though this varied by area of the country as to which was lowest, with off-brand Ultra bleach in some areas of the country being the least expensive.  Trichlor was a little more expensive.  Dichlor was much more expensive and lithium hypochlorite even more expensive.

  • Cal hypo is of course cheaper for the consumer and while dichlor and lithium have some advantages, particularly in vinyl liner pools, they can also get good results with cal hypo by simply dissolving it first in a bucket of water before applying it. I am not aware of "double grinding" but it has been awhile since I actively worked in the stores so that may well be true. Any PoolCorp guys out there who can verify this? Our main supplier for our products is PoolCorp and we have been very happy with their products and service.
  • I always premix, and walk around the perimeter of the pool pouring it in as I go. If you don't mix it and it's windy some of it doesn't make it into the pool .
  • Yes, I've seen that sort of pasty film on top of the water with some other chemicals as well and presume it to be something that is not water soluble so perhaps an impurity or binder chemical (especially for tablets -- I would think that granular/powder would not have binder, but perhaps not).  All of the listed chemicals in Cal-Hypo are water soluble (e.g. calcium hypochlorite, sodium chloride, calcium chlorate, calcium chloride, calcium hydroxide, calcium carbonate), but there can always be something extra in very small amounts.
  • Thanks Richard.

    I personally have never added shock without premixing. That being said, I still have some left on top of the water. I assume it is impurities from the remaining 22-27% of non-cal-hypo.

  • I calculated the maximum size of spherical Cal-Hypo granules that could possibly be able to float on the surface due to surface tension.

    (2.35 g/cm^3) * pi * R^3 * (9.81 m/sec^2) * (100 cm/m)^3/(1000 g/kg)) = 2 * pi * R * (71.97 milliNewton/meter) / (1000 milliNewton/Newton)

    Weight of particle = Surface tension against particle


    R = 0.0025 meters = 2.5 mm (0.1")


    In practice, smaller Cal-Hypo particles than this calculated amount will sink because the water isn't perfectly still and you are throwing product onto the water so it is falling and the particles aren't perfectly spherical.  Nevertheless, the principle is the same -- the finer the product, the more likely it is able to stay on the surface when you throw it onto the water.  The good news is that this should make pre-mixing with water easier since stirring should have it dissolve rather quickly.

  • If the granules are too small then they do not weigh enough individually relative to their edges touching the water surface to overcome the surface tension of the water so they float instead.  If the granules were pushed into the water, they would then mix and dissolve into the water -- they are dense enough to remain submerged once you overcome the surface tension.  The easiest way to add such product is to pre-mix in a bucket of water since you can stir it to break the surface tension.  It will then mix into the pool without a problem.
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