I believe its after its been opened once and the seal removed..... that's is why you don't want to keep it near metals when stored. The fumes will and can rust metals.
Maddie
Maddie

Yes, THAT I understand!!My own brand of MA wasn’t vented but many are. And my bottles were relying on that flimsy cardboard disk inside the cap to keep them sealed. It is only a matter of time before it’s vented unintentionally. It’s best to treat them all like they are. MA fumes are some nasty stuffs.
Pretty much no, no, and no. BUT.. I don't want to screw up either...Can you smell it upside down? Rightside up? In its storage area???
I have acid washed effervescence off a cinder block wall... yes I know exactly what you mean.. and its some nasty stuff!!I also just eyeball, but have been doing teaspoon chemistry for a long time, and have a better than average eyeball.I recommend measuring spoons/cups.
As for how nasty MA is, you have no idea until you have acid washed a plaster pool. Any of you who have know exactly what I mean.![]()
I’m sorry I have to come back to this. Many future readers will see this and possibly get a bad idea. *Never do THIS*. At best you are right and your bottle doesn’t leak/vent. You’ve gained nothing but a self pat on the back. At worst you are covered in Acid.Then why can I invert it, and squeeze it with no leakage
And you are probably right DONT DO THIS!!... And I have gained the knowledge that the caps are not vented which was the point.I’m sorry I have to come back to this. Many future readers will see this and possibly get a bad idea. *Never do THIS*. At best you are right and your bottle doesn’t leak/vent. You’ve gained nothing but a self pat on the back. At worst you are covered in Acid.
never
NEVER
Ever.
*end rant*. Back to your scheduled programming......
And that is all well and good in a pool situation, but this is in the hot tub section and amounts here are WAY smaller. an oz or 2 maybe three is all.I just dispense from the original jugs. ..except for the powdered stuff, I use a plastic measuring cup. When I first started I calibrated a ruler that showed me how much volume I would get out of a gallon jug. I would make a tic mark on the outside of the jug with a Sharpie at the current level of the liquid (MA or LC) then measure down to a pint, or a cup or whatever amount I needed and make a second tic mark. Then I would pour from the jug until I reached the lower tic.. And that was my starting point for the next time. Now I have an eyeball for it and I just make a smudge with my finger. And I pour to the smudge. I drop a lot less Sharpies in the pool that way.
No glass by the pool! If it breaks, it's almost impossible to get it all cleaned up. Use a plastic measuring cup.I dispense from the original tubs, too. Hubby took it a step farther. He bought cheap plastic doggie dishes to set my gallon jugs in. So I place the doggie bowl with the jug sitting in it onto the deck. Put on my chemical resistant gloves. Use the 2 cup glass measuring cup to measure with. And the measuring cup has it's own doggie bowl, too.
The doggie dishes are to keep any spills contained. No chemical spills and no pool water spills on our new decking!! And once more hubby came up with his own way of getting a pool water sample. I need to take a picture - It best explains. SOON!
Again, these guys are perfect! No pouring back and forth, no spillage, no chance of catastrophes.
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NOOOOO! Danger Will Robinson Danger!I only use the 2 cup Pyrex measuring cup for dumping MA or Chlorine in the pool. It's extremely sturdy and has a big handle. It's clear so I can see what I'm doing without getting too close. Honestly, if I'm shaky, I wouldn't be dumping MA into the pool!