Brands Of Shock

[davidandbess]

Hi which brands of Shock do you all buy, my local dealer sells Omni shock and it costs $5.50 per bag

and you an get Shock at walmart for $3 a bag.

Regards D/B

[waterbear]

First of all shock is a verb, not a noun. It is something you do to a pool (raising the FC levels to burn off organics and reach breakpoint), not a product you put into it. Unstabilized chlorine is usually the best thing to shock with since it won't raise cyanuric acid levels. There are three unstabilized chlorines--Sodium hypochlorite (liquid chlorine or regular unscented laundry bleach) which comes in strengths of 5.25%, 6%, 10% and 12.5% most commonly. This is the only liquid chlorine. It will not increase your calcium hardness nor cloud your pool. In granular form their are two different unstabilized chlorines. First lithium hypochlorite. It will not increase calcium hardness or cloud your pool and is very fast dissolving but it is the MOST EXPENSIVE form of chlorine to use. It's only advantage over liquid is the convenience of being granular. Second calcium hypochlorite or cal hypo. This is most commonly what is sold in the bags of 'shock'. It can also be used for normal chlorination. It is slow dissolving, raises calcium hardness, and can cause clouding of the water. It is sold in usually 43-48% , 62-68%, and in 73%. Walmart and the other 'big boxes' only sell the weaker stuff because there was a bad warehouse fire a few years back from improperly stored cal hypo! Most of your 'premium' brands are the 63-68% stuff, and there are a few that are the 73% stuff. The higher concentrations will raise a given amount of water to a higher free chlorine level for the same amount of shock. To put it another way, the lower conentration will raise about 7500 gallons to about 10 ppm FC, the higher concentrations will raise 10000 gallons to 10 ppm FC and the highest stuff will bump up that 10000 gallons another 1-2 ppm. This is why the walmart stuff is cheaper than the 'premium brand' stuff. BTW, walmart sells Aquachem, which is a Chemtura company brand. Omni is also a Chemtura company brand along with Bioguard, Hydrotech, Sun, and Pooltime (sold at Home Depot)! So the walmart stuff is made by the same company that makes Omni, it's just weaker!

Dichlor (one of the two stabilized chlorines) is also sometimes sold as shock (it is very fast dissolving so it's sometime recommended for vinyl pools for this reason) but I would not recommend using it for shock. For every 1ppm of free chlorine it adds it also adds .9 ppm of cyanuric acid (stabilizer). Using dichlor for shocking raises stabilizer levels very quickly and can lead to an overstabilized pool.

Hope this info is useful.