Weekly Shock?

[kelemvor]

I'm curious that my pool store recommends a weekly shock of the pool. Is this just a ploy to try and get me to buy chlorine?

I've got a salt system that's working well and since I got the pool clear a few months ago I haven't had any water quality problems at all. The generator keeps my chlorine levels up on it's own and I've been just putting acid in as needed, along with the occasional dose of polyquatchamacallit.

[aylad]

I'm curious that my pool store recommends a weekly shock of the pool. Is this just a ploy to try and get me to buy chlorine?



Yup.

Unless your CC is rising, or you are losing chlorine between sundown and sunup, or your water starts to look hazy, there's really no reason to shock, and certainly not weekly.

I shock my pool after I've had a couple of very busy bather load days, especially if there are very young kids or suspected pee'ers in the pool, and I usually shock it after hurricane-generated storms. Otherwise, save the chlorine!!

Janet

[chem geek]

Much of the pool industry recommends weekly shocking because they do not understand (or perhaps they do understand but don't want people to know) the chlorine/CYA relationship so they say that 1-3 ppm (BioGuard) or 1-1.5 ppm (GLB) Free Chlorine (FC) is all that is needed regardless of CYA level which can get to 200 ppm which they (BioGuard) say is just fine (but it isn't). The weekly shocking is a band-aid to kill off algae that has started to grow because the FC is simply too low relative to the CYA in the first place. It works for a while, but eventually doesn't work when the CYA gets too high.

Following the recommendations here, including Ben's Best Guess CYA chart (http://www.poolforum.com/pf2/showthread.php?t=365), will have algae killed faster than it can grow so will prevent algae growth using chlorine alone with no need for algaecides, phosphate removers, clarifiers, flocculants, or weekly shocking.

[kelemvor]

I've been using the chart. Right now I'm at 5ppm FC and 70ppm cya. I guess I'm a tad low, and I could bump the swcg up maybe 10 points to 60%. Thanks for the input on the shock; seemed suspect to me to need to shock if I'm not growing anything in the pool.

[waterbear]

With a SWCG FC levels a bit less than the chart work well. 4-5 ppm is perfect for a CYA of 70 to 80 ppm. Most salt pools never need shocking anyway.