Bleach vs Cal Hypo.

[houston]

I am new to this forum and very excited about BBB method and other the informative discussion here.

Yesterday I went to WalMart got its "GreatValue" regular bleach for $2.20 a bottle with 6% Sodium Hypochrolite. Each bottle is 1Gal 46oz. (about 1.3Gal). My pool is around 11200 Gal. I plug the number into Michael's Calculator. So one bottle of bleach will raise my pool Chroline by 7 ppm. This moring I went to a local Pool store, leslie. I found their Cal Hypoch power shock is at $127 for 100 lb. According to the instruction, 1 lb of this shock will raise Chroline by 1ppm in 80000gal pool. For my pool size 11200 or 7.15ppm. In other words, with bleach I am paying $2.20 for 7ppm, with store shock, $1.27 for 7.15ppm. Am I wrong somewhere ? Why would I go to bleach.

Thanks again for wonderful information in this website.

[chem geek]

Your numbers and analysis are correct. In this case, the CalHypo is an inexpensive source of chlorine. Using it, however, will increase the amount of calcium in your pool by about 70% of the chlorine amount -- so a rise of 1 ppm in chlorine also raises calcium by 0.7 ppm. So as a short-term source for chlorination, this isn't a bad option. For long-term or for shocking, you would need to watch your calcium levels and if they got too high you would have to do a partial drain and refill to lower it. Of course, you've got quite a lot of leeway before higher calcium becomes a problem -- several hundred ppm, perhaps a CH above 600 ppm though even then you might not see any scaling or cloudiness depending on your pool's other parameters.

Richard

[houston]

The strange thing is that last night I added 2.5 try to raise FC,TC to 15ppm at about 6pm (I don't have test kit). This morning I tested 2pm at 9am. then in the afternoon at 2pm. FC, TC back to 0. (these tests were done in the store). This means FC dropped very quickly. I got about 6hours sun during the day. How much bleach do you need in this area ? I saw some post says they add about a jug every other day. This means about 3.5ppm a day. This apparently not enough for my pool. Here are the numbers from this morning at 9am
TC=2
FC=2
PH=7.6
TA=140
HA=220
CYA=60
TDS=800

at 2pm ( I did in Texsun, which use alex testing machine bioguard)
temperature 90
Saturation idx: -0.1
TDS 900
CYA 120 (their reference is 30-200, bioguard system. don't understand)
TC=0
FC=0
ph=7.3
TA=162
Adj.Total Alk=126 (their ref. is 125-150, don't understand)
HA=170
quat=6

Can temperature play a big role in consuming chlorine this quick ?
If so, do it mean that I should probably wait till 8pm to add shock or bleach ?

Thanks.

[chem geek]

I suspect that the high chlorine levels bleached out the chlorine test, especially if it was just a DPD colorimetric test. High chlorine levels (> 10) need to be tested either with the FAS-DPD drop test or roughly with the OTO test or by diluting the water (with distilled water) before doing the DPD test.

Just goes to show what your pool store doesn't know.

Richard

[aylad]

The chlorine will dissipate quicker in warm water temps than cold, but you also may be fighting something in your pool that is causing the fast chlorine consumption. Just because you have 0 cc doesn't mean you don't have an algae bloom starting. And with a CYA of 60, a Cl of 2 ppm isn't enough to kee the algae at bay. If it were my pool, I'd shock it just in case...

Janet

[chem geek]

The strange thing is that last night I added 2.5 try to raise FC,TC to 15ppm at about 6pm (I don't have test kit).

Janet (aylad),

I may have misread what houston wrote (quoted above), but it sounded like he added 2.5 pounds of calcium hypochlorite to his pool to raise his chlorine to around 15 ppm (his pool is 11,200 gallons) though I calculate that it would raise the chlorine level to around 21 ppm (starting from 2 ppm). The numbers showing 2 ppm chlorine that he posted were before he added the Cal-Hypo. So his chlorine level should be extraordinarily high which is why I thought about the bleaching.

Thanks,
Richard

[dawndenise]

You really need a good testing kit so you can do whatever tests you need whenever you need them. YOU can maintain consistency better than a pool store. Store results, from a trusted store, can be used as a backup, or "second opinion", if you will. Leslie's, where you shopped, should have a good drops-based test kit for CL, pH, TA, CA, and CYA. They should also have a kit that will test for FC, as well. The kit on the Pool Solutions site is the best, IMO, but the Leslie's one will do for now. Walmart also has a similar kit for about $15, but I don't believe it tests for FC, only total CL.

Yes, it's best to add your chlorine in the evening when it won't be bombarded by UV rays, but don't be afraid to add it at other times, if you really need it based on your test results.

[aylad]

Chemgeek,

My understanding of his post is that "last night" he added the cal-hypo. At 9:00 the next morning he had 2 ppm Cl, and at 2:00 that afternoon was down to zero. I would think if bleaching was the problem, he also would have shown zero when he tested at 9:00 am.

Maybe I read it wrong....

Janet

[Spensar]

Houston,

In most cases bleach is less expensive. If cal-hypo is cheaper than that is fine, as long as you don't have calcium issues. You also don't have a bunch of bottles to recycle either. In my area, the bleach is a bit cheaper than that and the cal-hypo more expensive.

[houston]

Thank you all very much for great response. Finally my pool is back to normal after adding about 3 gallons of bleach every night and running pumps close to overnight.

One question remains: will Cal-Hypo add to TA or CH or both ? as to bleach, it only increases PH.