Dichlor / Bleach Query

[robquick]

Hi,

I've just switched to Dichlor/bleach having been using Dichlor for a while then moving to Cal-Hypo. As a result of this my CH is 240 and TA about 60.

Is there any risk using Bleach with CH so high ?

The manufactures recommended TA for my tub is 80-120, is it ok to use bleach with TA this high ?

If its not ok to use bleach with TA so high, is there any risk using the tub with TA between 50-80 when the manufacture recommends TA of 80-120 ?

Clearly when I change my water many of these questions will be irrelevant however, in the mean time I would like to know that everything is safe !!

Thanks

[john44111]

I just switched from a N2/Dichlor/MPS system to the PPP (or Dichlor/Bleach system) you are on.

From Page 2 of the Nitro's Approach to Water Maintenance

available here

http://www.poolspaforum.com/forum/index.php?showtopic=13634

There are four main parameters to keeping your water balanced. Water Temperature, Calcium Hardness (CH), Total Alkalinity (TA) and Potens Hydrogen (pH). Assuming your water temp is around 100 degrees, we'll just focus on CH, TA and pH. The best way to test these is with a Drop Test kit, like the one mentioned above. IMO Test Strips are just not accurate enough to test these, especially for a beginner.

Calcium Hardness: CH is basically the amount of Calcium in your water. The lower your CH, the higher your TA and pH need to be to have balanced water. The higher your CH, the lower your TA and pH need to be. The first thing you should do is test your CH in your tub. If you haven't filled your tub yet, test your tap water for CH using a drop test kit. If you have a water softener in your house, it will remove most of the Calcium in your water. That means you may get a different reading from your indoor sink then from the outdoor hose. Check both to make sure. If you have really bad well water i.e. lots of metals etc., you may want to fill your tub using the water softener water, then just add Calcium afterward. If your water is city treated water, you may be ok straight from the hose. Also, consider getting a pre-filter that attaches to your hose, and filters out some of the metals.

Here's my recommendation. If your CH is much below 100 ppm, you should add calcium to bring it up to 130-150 range. If your CH is over 100, you can leave it alone and just make a note of what it is.

my CH is 100 (City of Cleveland Water) I didnt have any CH issue.

[chem geek]

The main risk of having the higher CH, especially if the TA is also higher (i.e. in the "normal" range recommended by manufacturers) is that if the pH goes higher then you can get calcium carbonate scaling, especially in the heater. If you keep the TA lower, closer to 50 ppm, and if you use 50 ppm borates (most easily added from boric acid), then this should keep the pH more stable and prevent it from getting too high. If you keep your TA low, use borates, and keep an eye on the pH, then your CH of 240 ppm will be OK.

The main issue manufacturers have with a lower TA is that the pH can bounce around more and if it gets low then it can corrode metal equipment. That isn't an issue when using a hypochlorite source of chlorine since the pH will tend to rise and not fall (unless you are using other chemicals that are net acidic). Also, the 50 ppm Borates are a supplemental pH buffer for stabilizing the pH.

You should find that using bleach is very similar to using Cal-Hypo except that you don't get a buildup of CH. The bleach might have the pH rise more quickly depending on the brand of bleach since some have more "excess lye" in them. Clorox brand tends to have the lowest amount of "excess lye", but it also tends to be more expensive (though for spa quantities, it's still pretty darn cheap).