Need to wait between adding bleach and muriatic acid?

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jamescookmd

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Apr 10, 2018
11
San Jose, CA
I'm about to drain my pool and start TFPC. Historically my pool has a tendency for pH to drift up. I add about 1/2 gal of 20 baume muriatic acid every week.

Since I'm switching to bleach, I'm anticipating the pH drifting up even more quickly. Does that happen with TFPC?

Also, it's dangerous to directly mix bleach and muriatic acid. So if I need to add both, how long do I wait between adding them? Can I add them simultaneously in different areas of the pool?

Thanks,
James
 
James,

You are good as long as you don't add them at the same time in the same spot...

If you were using tabs before, than you should expect to see your pH increase a lot when you switch to Liquid Chlorine.

I suspect that you have water features that you are constantly running... Aeration is what you do when you want your pH to go up... :p

Thanks for posting,

Jim R.
 
Thanks for the tips on chemicals.

Re: pH. Nope, no water features. Pool was re-plastered and refilled 2 years ago. CYA is through the roof (which is why I'm draining and restarting) but otherwise things are pretty balanced, pH 7.5, FC 4.5, CC 0, TA 120, CH 650. I've never been able to figure out why the pH keeps drifting up -- I expected that for a few months after the re-plaster, but 2 years later I'm at a loss.
 
Yeah, you will need to lower that TA. I’d try 80ppm at first and if you still don’t like the pH rise rate, lower it to 60ppm. You can go as low as 50ppm but it’s hard to maintain that if your fill water has high TA.

Can you post your fill water TA and CH?
 
And when Jim says at the same time in the same place he literally means at the exact same time. The only time I leave between adding bleach and the acid is the time it takes to close one bottle and go over and get the other bottle. It is perfectly safe once it is in the water.
 
TA can vary quite a bit depending on the municipal suppliers desired saturation target. Your TA is about 40ppm higher than mine but my CH is easily twice your value. That TA you have is high enough to drive your pH up when you switch over to bleach and you will experience greater pH rise when evaporation is high (summer months). Look around for a HASA chemical supplier in your area as they will typically offer acid in four 1 gallon refillable containers. It’s usually cheaper that way and then you don’t have lots of empty jugs to throw away.
 
jamescookmd said:
@JoyfulNoise - fill water is San Jose tap water. I measured out of a garden hose. pH 7.8, TA 140, CH 120.

Do those numbers make sense? TA seems kinda high, but I don't know what's expected of tap water.
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That's normal for San Jose. All the tap water comes from wells and it's pretty hard. (I lived in San Jose for the first 45 years of life)

Once you get TA down to where you want it, you'll learn your pool's appetites. For me, it's a quart of acid for every 2" of refill water.
 

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Wait on adjusting your TA until after your drain and refill. Your fill water numbers are quite decent. My TA is 230 and my CH is 300 here in South San Jose near Capitol Auto Mall.

I did a drain and refill last spring and aerated my pool down to 70. It took a while to get it there from 230.
 
jblizzle said:
And when Jim says at the same time in the same place he literally means at the exact same time. The only time I leave between adding bleach and the acid is the time it takes to close one bottle and go over and get the other bottle. It is perfectly safe once it is in the water.
Click to expand...

Not necessarily- when an acid column crashes into a chlorine column, you will surely know.

Eyes,
Lungs & mucus membranes will let ya know on a foggy humid day..

Play it safe & take a your time.
 
PoolguyinCT said:
Not necessarily- when an acid column crashes into a chlorine column, you will surely know.

Eyes,
Lungs & mucus membranes will let ya know on a foggy humid day..

Play it safe & take a your time.
Click to expand...
If you are pouring the liquid slowly in front of a return jet as recommended, it becomes mixed with the water right away. No worries adding the 2 chemicals within minutes of each other.
 
Chemical handling & post application incidents
occur every year. & reactions of incompatible chemicals below the water are included.

They are usually detected as a “gas blanket” above the waterline. & generally public pools, as very few residential incidents make it to the CDC complication.

Mishandling of chemicals, untrained operators and dispensing equipment failures are always cited.

I’m just saying, for safety sake give it a few minutes.
 
PoolguyinCT said:
Chemical handling & post application incidents
occur every year. & reactions of incompatible chemicals below the water are included.

They are usually detected as a “gas blanket” above the waterline. & generally public pools, as very few residential incidents make it to the CDC complication.

Mishandling of chemicals, untrained operators and dispensing equipment failures are always cited.

I’m just saying, for safety sake give it a few minutes.
Click to expand...
I think we all agree on being safe when handling chemicals and are basically saying the same thing here.

If one add chlorine as TFP recomends (pencil thin stream poured in front of a running return jet) the chemical is dispersed and mixed almost immediately. Then factor in the time to close the chlorine bottle, get the acid bottle and again, slowly pour in front of a running return jet there is sufficient time factored in to be safe.

I would hazard that any residential pool accidents were from splashing the chemical from pouring too quickly, pouring/mixing the chemical in buckets and the like.

I quickly went over the CDC pages regarding pool accidents and found great disparity on their reported information. On one page I found information on a study that found 400 pool related chemical accidents over a six year period , but on a beginning summer press release they were stressing safety by saying that "thousands" of people require hospital visits each year because of pool chemical accidents. Hmmmm, I think they need to get their facts together. I would be interested to see any accident report for "reactions of incompatible chemicals below the water" as this seems one of those things that is probably more urban legend than fact.
 
They won’t segment between above & below water. When evacuations , air quality metrics, and bather counts are noted - that is the closest indication to the incompatibles reacting in the pool water.. & obviously it is operator error or mechanical dispensing defect.

Btw - I’m not a doom & gloom guy.
What I have learned is common sense, isn’t to be relied on.. it sounds funny, but regulations & policy are written with the assumption common common sense will not be a factor. Human factor is just too much of a wildcard.
 
duraleigh said:
Sorry if I am missing something....I still have not heard of chlorine and acid "columns".......what does that mean?
Click to expand...

Sorry I spaced on that ?

...simply high concentrations of chemicals that have yet to be dispersed in the pool water..

Like the old school acid “slug” where the user pours a straight column of acid with a steady hand, believing the fallacy it’s gentler or safer for the finish & handler.

Ray
 
PoolguyinCT said:
Btw - I’m not a doom & gloom guy.
What I have learned is common sense, isn’t to be relied on.. it sounds funny, but regulations & policy are written with the assumption common common sense will not be a factor. Human factor is just too much of a wildcard.
Click to expand...

Nether am I, but there is one thing I’ve learned walking around this rock for 48 years is...
”Common sense is the LEAST common of all the senses”
 

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