Premixing Dry Acid

[FredFredrickson]

I have some Dry Acid (which I know, I'll be switching to Muriatic when I can get my hands on some), and the bottle from walmart says pretty plainly, don't pre-mix, add directly to water. Well, I don't know if I didn't wait long enough after adding chlorine but the smell that came up off that was quite bad, I had to take a few steps back.

So reading here, I see I should be premixing- but there's a problem, the water out of the tap here is still 2ppm FC (and that's an issue with something they've done to the aquifer as I understand it).

So question 1: How dangerous is this gas i just smelled?

Question 2: Is premixing it in 2ppm FC going to be an issue?

 

[BenB]

I don't have great answers to your questions but here's a stab.

1) The fact that you smelled it and presumably either then held your breath or moved away means your body did it's job and you avoided doing any damage. Not that bad is basically the answer.

2) Given the water has no CYA in it, perhaps fill a bucket and leave it in the daylight for a few hours / day. It won't have any FC left in it after a little while.

 

[Donldson]

So reading here, I see I should be premixing

I am not sure where you are seeing this posted here. Premixing dry chemicals is generally discouraged as a whole here.

 

[FredFredrickson]

I am not sure where you are seeing this posted here. Premixing dry chemicals is generally discouraged as a whole here.

Recommended to pre-dissolve in a bucket: Recommended Pool Chemicals - Trouble Free Pool

 

[jmastron]

I don't have great answers to your questions but here's a stab.

1) The fact that you smelled it and presumably either then held your breath or moved away means your body did it's job and you avoided doing any damage. Not that bad is basically the answer.

2) Given the water has no CYA in it, perhaps fill a bucket and leave it in the daylight for a few hours / day. It won't have any FC left in it after a little while.

Agree with #1 except that if you smell fumes you should not just hold your breath, but move away fairly quickly. There was a guy here a couple years ago who wore a good full respirator dosing with Muriatic Acid. He didn't smell anything so poured for probably a minute, but his eyes were burning afterward and he had some damage that his opthomologist could see (temporary I hope). I think he was wearing goggles, but those protect from splashes; they aren't generally airtight (swim goggles might be, but you won't really know if you have them sealed when not in the water). Best to have your sense of smell, which reacts faster, in play.

I've never used dry acid, so don't know if it can react as it goes in the water and fume similar to liquid, regardless of chlorine level. I'm not a fan of premixing or "broadcasting" chemicals around the pool in general (I figure I'm a lot less likely to trip/spill anything if I'm stationary on the deck in front of a return), but it does seem like TFP recommends premixing for dry acid and borax. I'd give it a try -- don't do it on the concrete deck, do it on the lawn or dirt. If you smell the fumes just move away temporarily until the smell dissipates.

One neat thing I found was pouring MA at night with a headlamp, I could see the fumes coming off the water, so it was easy to tell how much and what direction. Now I no longer pour MA into a measuring cup (I have a stick to mark quart lines on the side of the jugs, then just pour straight from the jug an inch above the water.

 

[Donldson]

Recommended to pre-dissolve in a bucket: Recommended Pool Chemicals - Trouble Free Pool

My mistake. I'll have to have a word with someone about that, because I whole-heatedly disagree with that.

 

[FredFredrickson]

My mistake. I'll have to have a word with someone about that, because I whole-heatedly disagree with that.

My normal method is to slowly pour it into the water return and it seems like none of it ends on the pool floor that way.

That said, I've never had an outgassing like that before so I don't know if I should be as close to it as I was.