Muriatic Acid and other chemistry questions

[spork]

Hello,

I purchased a new 300g tub and awaiting delivery. Had a few questions.

I might try half strength muriatic this time around. However it does get cold enough to freeze here vs full strength. Does it matter if the bottle freezes? Not sure how likely the bottle would be to burst if frozen?

On a fresh fill my ta is very high. With my 220 gallon tub it would take 10 - 12 oz of dry acid to bring it down. If I wait 30 minutes between additions this makes refilling the tub an all day event. If aeration brings the ph back up would it be safe to reduce the time a bit? How long to wait before adding dichlor after the final addition of acid? Waited 30 minutes previously.

With my last tub I figured out how many tsp of dichlor would give me 30 ppm cya and switched to bleach. Water was always crystal clear and never needed to replace the cover. I rarely tested for cc. Only a few times did it seem like the tub was eating FC so I used ahhsome and did a refill. How often should I be checking cc? I havent needed mps so far.

I use the taylor 2006 test kit but might pick up the 1001 for quick checks.
edit: My calcium hardness is very high as well. Last time iirc its between 220 - 260 ppm.

thanks for the help

 

[PoolStored]

Not sure how likely the bottle would be to burst if frozen?

Not sure where you are located. I would be concerned about the 15% bottle bursting and draining acid, I'd be unconcerned about full-strength. The freezing point of full-strength Muriatic Acid (31.45% Hydrochloric Acid) is -46ºC (-50.8ºF). Half-strength Muriatic Acid (15% Hydrochloric Acid) has a freezing point of -18ºC (-0.4ºF).

 

[spork]

I'm in northern IL. I will stay with full strength then should I decide to use it. I need to figure out some sort of locking vented container for storage. Would it be ok to dilute with water when used or is there any point? Not sure if it would be any safer pouring directly into a measuring cup or having some water in it ahead of time?

 

[phonedave]

If I am reading this information correctly

Hydrochloric Acid Storage Tanks & HCl Specifications

Hydrochloric Acid Storage Tanks are manufactured from XLPE, HDPE, FRP and rubber lined carbon steel to 1.9 SG. Secondary containment is required. Thermoplastic fume scrubbers and vents should be used...

www.protank.com

In the table "Hydrochloric Acid Density in g/cm3" about half way down

30% HCL at 60C has a density of 1.1260 g/cm3

at -5C it has a density of 1.1648 g/cm3

Which means it is getting denser (contracting) as it gets colder.


Actually now that I think about it, that means nothing. Water behaves the same way. It is the crystalline structure it sets up at freezes that causes it to expand, up until freezing it actually does get denser as it gets colder. You would think the years of wastewater modeling would have stuck with me longer.

So I have no idea what HCL does when it freezes

 

[PoolStored]

I need to figure out some sort of locking vented container for storage.

Yep.

Would it be ok to dilute with water or is there any point? Not sure if it would be any safer pouring directly into a measuring cup or having some water in it ahead of time?

Handle muriatic acid only once pouring from the jug into the pool/tub (less handling and risk). Don't be afraid of MA, be respectful. Even full strength if you get it on you hand/arm, just dip in the tub. DO wear safety glasses/goggle. DO pour downwind. DO pour slowly. This is a really good read:

Acid - Further Reading

www.troublefreepool.com

 

[phonedave]

If I am reading this information correctly

Hydrochloric Acid Storage Tanks & HCl Specifications

Hydrochloric Acid Storage Tanks are manufactured from XLPE, HDPE, FRP and rubber lined carbon steel to 1.9 SG. Secondary containment is required. Thermoplastic fume scrubbers and vents should be used...

www.protank.com

In the table "Hydrochloric Acid Density in g/cm3" about half way down

30% HCL at 60C has a density of 1.1260 g/cm3

at -5C it has a density of 1.1648 g/cm3

Which means it is getting denser (contracting) as it gets colder.

10% HCL exhibits the same behavior

 

[PoolStored]

Which means it is getting denser (contracting) as it gets colder.

Generally, when something that is a mostly water solution freezes, the solution expands, just like water does. Often, the solution crystallizes out at least some of the pure solute and pure water, (although mixed ice can occur, as well as ice with inclusions.) A 35% solution of hydrogen chloride gas in water isn't a separate compound, unlike for example 98 % pure sulfuric acid.

 

[spork]

How difficult is it to measure a few oz or less when pouring directly from the bottle?

 

[PoolStored]

With 300g, your acid quantities are miniscule. Just to make it easy to work with, I would use dry acid. For a pool, using dry acid is not as favorable because of the steady accumulation of sulfites. In a hot tub, you will dump the water often enough to render that issue irrelevant. Use dry acid.

Or, get a PLASTIC measuring cup, pour your ounces needed into the measuring cup (over the tub please), then pour out the measuring cup into the tub and dip the measuring cup in to rinse. I'm not afraid of MA, just respectful.

Dry acid, in your situation, makes sense.

 

[phonedave]

Hello,

I purchased a new 300g tub and awaiting delivery. Had a few questions.

I might try half strength muriatic this time around. However it does get cold enough to freeze here vs full strength. Does it matter if the bottle freezes? Not sure how likely the bottle would be to burst if frozen?

On a fresh fill my ta is very high. With my 220 gallon tub it would take 10 - 12 oz of dry acid to bring it down. If I wait 30 minutes between additions this makes refilling the tub an all day event. If aeration brings the ph back up would it be safe to reduce the time a bit? How long to wait before adding dichlor after the final addition of acid? Waited 30 minutes previously.

With my last tub I figured out how many tsp of dichlor would give me 30 ppm cya and switched to bleach. Water was always crystal clear and never needed to replace the cover. I rarely tested for cc. Only a few times did it seem like the tub was eating FC so I used ahhsome and did a refill. How often should I be checking cc? I havent needed mps so far.

I use the taylor 2006 test kit but might pick up the 1001 for quick checks.
edit: My calcium hardness is very high as well. Last time iirc its between 220 - 260 ppm.

thanks for the help

1. Thinking about this further, I would be more concerned with the MA partially freezing and the remaining part now being a greater (unknown) concentration. You could always just keep the jug partially full, and for even more protection, keep the jug in a plastic tray to catch anything that may leak out, and for even even more protection, spread a thick layer of baking soda in the tray before placing the jug in it.

2. You don't want you pH to get too low, so you will need to wait between acid additions (dry or otherwise). I bring mine down to around 7.2 and wait for it to get back up before re-adding acid. My starting TA is about 140. It takes me about 5 oz of 14.5% MA to bring it down. I normally add that over the course of a week. I my be wrong here, but I add dichlor to my tub 5 minutes after adding acid (with the jets on high)

3. You should, but I don't all of the time either. I do the same process as you.

4. For me a high (300) CH is desirable. Otherwise my Aqua Clarity foams all over the place.

 

[spork]

I was digging through some other posts and it seems 30 minutes is the suggested waiting period between additions of acid and no less. Nitro's guide and other posts seem to think lowering the ph down to 7 is fine during the balancing process. I've always done it on the same day and didn't know others did it over a week or so. I usually go for a ta of 70 ish on the first day and let the dichlor lower it down from there with minor additions of the dry acid as needed.

if it gets too dark I will add the dichlor 30 min after the last addition of acid and continue balancing the next day. I don't want the tub to sit overnight with no chlorine.

I also discovered my local store sells full strength in quart bottles. Wish they had small amounts in the weaker stuff that way it could be used up before it gets cold.

 

[Methuselah]

With TA that high I'm betting you will use several ounces minimum of full strength MA, so recommend you get that and not have to worry about it freezing. Got mine fairly inexpensively at Lowe's by the gallon. It can also be used to wash concrete

As to your question about dilution, it's my understanding you never pour water into acid, but the other way around is OK.

It took me a week if I recall correctly the first time to get all the CYA, MA and aeration stuff done. I think I did it mostly an ounce at a time into 515 gallons. Second time faster with 2 ounces at a time. On the high CH, can't you pre-filter? I think with an acrylic tub high CH is acceptable, but ~240 ppm seems like a lot if you don't have to...

You know, I'm betting you can do CYA first with dichlor, and if the dichlor pushes ph, adjust gradually with the MA and probably use the tub while in the process? Just be sure to keep fc commensurate with the CYA levels (watch the minimum).

 

[Mdragger88]

When lowering ta in my spa I usually aim for a ph of 7.1 then aerate to 8.0 & repeat. Each cycle lowers the ta by a dab more each time. Once it’s under 80 each round usually lowers ta by 10ppm. I use full strength ma & a plastic adjustable measuring spoon to measure it pouring it into the spoon whilst over the water incase of spillage then rinsing the spoon, setting it aside & capping the ma bottle then rinse off the ma bottle if there were drips. I do also use the dichlor as a helping hand to lower ta. I generally do it over a couple days. There’s really no rush.

 

[Cousinvinny]

This is what I use, 32 oz. I don't believe it's vented.

Tip n Pour Measuring Bottle

 

[phonedave]

I was digging through some other posts and it seems 30 minutes is the suggested waiting period between additions of acid and no less. Nitro's guide and other posts seem to think lowering the ph down to 7 is fine during the balancing process. I've always done it on the same day and didn't know others did it over a week or so. I usually go for a ta of 70 ish on the first day and let the dichlor lower it down from there with minor additions of the dry acid as needed.

Is that for a pool where circulation/mixing takes a lot longer?

With my spa jets on high, my water is thoroughly mixed pretty quickly. I use a pH meter to check pH. I can add acid with the jets on, and a few minutes later get very consistent readings across the whole spa.

 

[spork]

nitros guide said 30 minutes between additions which is what I've tried to follow.
I read this post and I think it does refer to pools but it also says 30 min.

How to lower TA

For a quick overview of the process, see the Pool School article How To Lower Total Alkalinity. There are two reasons to lower your total alkalinity (TA) right away, because you want to slow down the rate that the PH rises, or if high TA is contributing to a high calcium saturation index (CSI)...

www.troublefreepool.com

My ph rises very fast the first few days because the tub keeps running until it heats up. I don't know how fast scaling can be a problem? which is why I try to get the ta lowered asap.
Maybe having a meter would be helpful so I can test more frequently to determine how long it takes the ph to rise.

I picked up a 32 oz bottle of muriatic. Along with a adjustable spoon, gloves, and I already have goggles. Dry acid would get very clumpy fast so I think the liquid will be easier to work with. I think dry has more of a delay in working until it dissolves all the way? Sometimes I would pre mix in water but it still didn't like to dissolve.

I still might use dry for regular fine tuning and muriatic during the initial balancing.