Adding 20-30 gallons of bleach per week. How to save money?

[ltfdrebbin]

Are you in full sun each day?

My pool at a cya of 80 will sometimes use 3ppm per day on sunny days (its in full sun from 11-5 pm.

I found a way to reduce my chlorine consumption massively...in fact over the last two days I have lost
maybe 1ppm in full sun.

the solution?

blue solar cover. It's blocking the UV rays so I might be adding 1 gallon of bleach per week now
with no bather load. thanks to the cover.

I'm also not losing any water to evaporation....with the cover off, I had to top the pool off
every 7 days.

We are in full sun all day.
We keep the cover on except for when we are using the pool, but it is a clear cover.
Does a colored cover really reduce chlorine consumption?

 

[OldPoolBoy2]

Yes it will reduce chlorine "consumption" An opaque cover (blue is one of them) will reduce the UV waves from entering the pool. (The clear cover allows a good percentage of them to penetrate).

 

[chem geek]

Thanks for the knowledgeable comments. If I change my FC target to 6, and still lose 3.5 per day, do I end up growing algae at that level- or even lower if we have a lot of swimmers on a sunny day?

You shouldn't lose as much FC per day. If you did, then there wouldn't be much point to having a lower target. You want to make sure that whatever you target you always stay above the minimum FC/CYA level so at 80 ppm CYA that means 6 ppm FC. So you should raise the FC so say 9 ppm and see if it stays above 6 ppm. If you only lose 2 ppm FC then you can go from 8 and add more chlorine the next day when it gets to 6.

 

[ltfdrebbin]

I disconnected the ozonator last night around sunset.
This morning, my FC tested at 5 (CC .5), and I added 363 ounces (almost 3 gallons) of 7.86% bleach. This should have taken our FC to 10.5.

The pool was covered all day. Nobody swam in it.
It was sunny, and my solar cover is clear.
I ran my deck jets for aeration most of the day (not sure it matters).
My automatic cleaner was in the pool all day, and the cartridge filter has been running for 4 weeks straight (except for a cleaning I did 2-3 weeks ago).
At sunset tonight, here are my readings:
FC 4
CC .5
CYA 75 (earlier this week we added 2.5 inches of water- garden hose for about 6 hours).
PH 7.2
TA 220
CH 310

All of my other numbers are staying pretty consistent, but what is happening to all of the FC? The water is still crystal clear, and the CC is still .5.

Thanks again!

 

[chem geek]

When you add chlorine, do so with the pump running and then test the water after at least 30 minutes. That will confirm that the chlorine you are adding is as strong as you think it is.

Also now that you've tested at sunset, I'd get your FC back up, measure after 30 minutes, then see what you measure early tomorrow morning for an overnight chlorine loss test. This will say whether the loss is mostly from sunlight or is something else in the pool consuming chlorine.

Maybe the aeration is outgassing chlorine, though usually it won't be that much. After you measure tomorrow (and get the FC back up if needed) you can see what happens with the deck jets turned off.

 

[ltfdrebbin]

FC 4
CC .5
CYA 75 (earlier this week we added 2.5 inches of water- garden hose for about 6 hours).
PH 7.2
TA 220
CH 310
!

The readings above were from last night. I added enough bleach to take the FC to 10.5.
This morning, I was at 7.5 FC, and 0 CC. I spread 121 ounces around 60% of the pool, and left the pump running.
40 minutes later, I tested again. I was at 8.5 FC, and almost (it was a very light pink) .5 CC

Is the chlorine not really 7.86% available?
Any other thoughts?

Thanks again

 

[OldPoolBoy2]

If you are losing 3 ppm overnight you have something in your pool growing. You need to test after sun goes down and then test in the AM before or just before sunrise in the dawn. You need to confirm your FC level at night after you have added it (30 mins min), and confirm it in the AM. If you have more than 1 ppm loss you have something growing. (OCLT)

Chem Geek post #25 is worth re-reading and following.
Hang in there.

 

[ltfdrebbin]

Nobody swam today, and the pool cover was on all day.
After sunset, I did a test.
FC 3
CC .5
I added 425 ounces (3.5 jugs) of 7.86%

I waited 35 minutes and tested again.
FC 7
CC .5

ChemGeek- does this mean that the chlorine is not really 7.86% Would it be about half that?

I added an additional 605 ounces (5 jugs), on the assumption that if the available chlorine is closer to 4 than 7.86% as advertised, I'd only be taking my FC to about 11.6. Am I understanding this correctly? Does it seem like the problem is a weaker percentage of available chlorine in the jugs I've been buying from Wal Mart?

Thanks

 

[chem geek]

425 fluid ounces of 7.86% in 42,000 gallons should raise the FC by 6.5 ppm FC, but you found it only went up by 4 ppm so assuming your pool water volume is correct the concentration of your bleach is more likely to be around 4.8% (so closer to 5% than 4%).

Your additional 605 fluid ounces if consistent with the earlier bleach would raise the FC from 7 ppm to 12.7 ppm.

So at least part of the problem of high usage seems to be that the chlorine isn't as strong as you think. However, if you do an Overnight Chlorine Loss Test (OCLT) and find you lose significant chlorine with no sun on the pool, then that is a problem not related to the lower concentration of bleach.

 

[Bloomfield]

This is another possibility. Doesn't bleach lose it's effectiveness over time?

When it's hot I will use that barrel in about a month. It might lose a little effectiveness. I just pour a little more in. It doesn't seem to be a problem.

 

[ltfdrebbin]

Your additional 605 fluid ounces if consistent with the earlier bleach would raise the FC from 7 ppm to 12.7 ppm.

Thanks for help figuring out the concentration of bleach. I now wish I had stayed up another 30 minutes last night and done another test.

OCLT results:

FC 16.5
CC 0

I believe the volume of water calculation to be correct. We've had the pool completely drained and refilled, and both times the truck driver confirmed 42,000 gallons.

Still trying to figure out what is going on:
CC continues to be 0, or .5.
So am I getting different concentrations of bleach from the same shelf at the same Wal Mart? Or is there something more I should check/ do?

Thanks everyone- and especially Chem Geek!

 

[ozdiver]

How old the bleach on their shelves is will influence it strength.
Batch numbers can be decyphered to work out relative age of the stuff.
I found by shopping around that I was getting better bang for buck by buying liquid shock from Home Depot. It it 10% could be bought by the case of four @ $16.46.
Worked out that is was beating my Walmart for amount of active ingredient.
I since found a bulk supplier that I fill up a couple of 7gal containers with their 11% bleach for even less. I am down to $1.68 /gal of this stuff.