How much Chlorine/Bleach is normal usage?

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tjf120

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Apr 27, 2013
18
I live in Houston, TX. So its getting hot out ~95 F this week.

Pool - plaster lined, 18,000 gals, use ~3/week

I'm using the BBB method (well, no Borate yet). I use a Taylor 2006 test kit. CYA ~45-50

I'm using 10% bleach, ~$3 gallon. I'm going through a gallon every 1-2 days. That seems high? How much bleach is 'normal' usage?
 
That much huh? Granted my pool is 5x smaller than yours HoleInOne, but I use about a cup per day of 8.25% bleach. Times 5 to equal the same size pool as yours and that gets you a little over 1/4 of a gallon per day. That's at a CYA of 30.

But it seems logical that the larger the pool surface area, the more chlorine the sun has a chance to burn off as there's more exposed surface water. Not just the total volume of water linearly. Ie. It doesn't scale that way.

The 10% bottles have a shelf life of around 6mo or so, depending on the conditions they're stored in. The 8.25% bottles are about a year.
You can test them with a test kit from Taylor specifically designed for testing higher concentration chlorine sources, but It's a bit spendy. Cheaper to use some 1ml pippettes and a few large mixing beakers. Search the forum for Chem Geek's instructions.
 
We're using 10%, approx. 36 to 40 oz. per day, with a 2ppm Chlorine drop daily, with CYA at 50ppm.
At 15,200, we equal about 84% of your pool in gallonage.
All other things being equal, you would likely use about 43 to 48 oz. of 10% per day to maintain the 5-6ppm FC that we do.
So, I have to agree, as JasonLion says, there's something else going on with your pool.
 
I added 2 lbs of Cal Hypo last night, results tonight (Taylor 2006)

FC - 6
ph - 7.4
CYA - 45-50
Alk - 90
Ca - 300

I buy the shock, I double checked, it is $4/gal at pool store, sold at 10% 'pool shock'. They go through a pallet a week it looks like, there does not appear to be a date on the bottle, or the box it came in. There is a code on the bottle, could have some date info in it.
 

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Ok, so bleach should be ok based on date, still going through a lot of chlorine. I 'super-chlorinated' a couple weeks ago to kill some black algae. Haven't seen any new blooms, still scrubbing a few spots where the black is in the plaster (ie, the plaster is somewhat porous, black is below the 'surface' of the plaster)
 
Do you really want a FC of 6. I'm new to pool maintenance but I'm trying to stay between 1-3 with no CC. 7.4-7.6 ph and my borate is at 60 ppm and my CYA is at 40. When/why should I add shock?
 
terryc said:
Do you really want a FC of 6. I'm new to pool maintenance but I'm trying to stay between 1-3 with no CC. 7.4-7.6 ph and my borate is at 60 ppm and my CYA is at 40. When/why should I add shock?
Click to expand...
See the Chlorine / CYA Chart in the Pool School. If you have only 1 or 2 ppm FC with 40 ppm CYA then algae can grow faster than chlorine can kill it. You can get lucky, but you should be keeping your FC at a minimum of 3 ppm at all times so that means higher than that at times unless you have an automatic dosing system. The borates in your pool do act as a mild algaecide, but we've never worked out precisely how much lower you could have your FC when you have borates, but it's not that much.

What the pool industry doesn't tell you is that when there is CYA in the water, most of the chlorine is bound to it essentially inactive. It is the unbound active chlorine that kills algae and disinfects the pool, but to get enough active chlorine you have to have a higher FC level when the CYA is higher. Recommending an FC range independent of the CYA level is completely ludicrous, yet that is what the pool industry touts -- with the result of a very profitable industry selling algaecides, phosphate removers, clarifiers, flocculants, enzymes and "shock" products that are nothing more than higher margin chlorine products identical to other chlorine products with the same chemicals.

If you properly maintain the appropriate FC level for your CYA level then you should not need to shock your pool on a regular basis. You would only shock if an unusual circumstance occurs. Many members only shock their pool when they open the pool during spring. I haven't needed to shock in a few years because I keep chlorine in my pool over the winter (it doesn't freeze).
 
tjf120 said:
I 'super-chlorinated' a couple weeks ago to kill some black algae. Haven't seen any new blooms, still scrubbing a few spots where the black is in the plaster (ie, the plaster is somewhat porous, black is below the 'surface' of the plaster)
Click to expand...

Did you follow the shock procedure in pool school, and only stopped once you passed all 3 criteria?
Shocking is a process, not a product you dump in the pool.

Also, are you sure it is black algae? Ba is slow to appear and just as slow to go away, as it is highly chlorine resistant. It grows in layers with a hard shell between each layer. Chlorine alone will not kill it, a stainless steel brushing daily, multiple times per day is necessary to break off its CL resistant shell so the CL can then get to it. Layer, by layer, by layer. You keep the pool at shock levels until it is gone.

To verify you have BA, scrape it with your finger and smear it on a piece of paper. It should leave a dark green and black smear behind. You can also take a trichlor or dichlor tablet, place it in a sock and weigh it down on top of the spot for 1hr. After one hour, remove tablet and sock, checking the black spot. If the stain lightens from the bleaching, then its BA.
Do not leave the tablet for longer than 1hr.
Ask 1st if you have a colored plaster pool, as I'm not sure if that test is OK in such a situation.
 
tjf120- I am in Cypress and I am currently going through 1 jug (121oz) of 8.25% per day. For my pool (28,000 gal) that works out to just under 3ppm of Cl per day. My CYA level is around 40. During cloudier times I still add 1 jug but can skip a day every 3 or 4 days.
 
y_not said:
tjf120 said:
I 'super-chlorinated' a couple weeks ago to kill some black algae. Haven't seen any new blooms, still scrubbing a few spots where the black is in the plaster (ie, the plaster is somewhat porous, black is below the 'surface' of the plaster)
Click to expand...

Did you follow the shock procedure in pool school, and only stopped once you passed all 3 criteria?
Shocking is a process, not a product you dump in the pool.
Click to expand...

If the 3 criteria are
Repeat steps 3 and 4 as frequently as practical, but not more than once per hour, and not less than twice a day, until:
1 - CC is 0.5 or lower;
2 - An overnight FC loss test shows a loss of 1.0 ppm or less;
3 - And the water is clear.

Yes, shocked for ~10-14 days, chlorine levels of 15-30 ppm during the duration.
 
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