Please read - I'm very anxious for any theories, or support of mine, re: leaching of muriatic acid causing thousands of dollars worth of damage in my crawl.

A year ago I had a new high efficiency heat pump installed. The inside unit is in the crawl under the house. In the first section of the crawl (where you can actually fully stand) is a cement patio, and this is where I have always stored my pool chems, including jugs of bleach, muriatic acid, and CYA. I live in Alabama and the garage and pool house just get so hot, the cool crawl seemed like the place to keep it.

Recently when we had a brief dip in temps I cycled on my heat for the first time since last Spring. Was I ever surprised when I saw everything in the house coated with tiny white flakes. A couple days later I put the AC on and the pungent smell of mold filled the air. I called my HVAC guy, David, and he began disassembling the inside unit in the crawl. The evaporator coil was filled with the stuff (in fact, ruined), likewise all the duct work including two new ducts I had done a year ago (I was going to replace 2 each year). The 30-year-old, fiberglass main trunk line was also full of it, and unfortunately, also black mold (presumably an unrelated and second problem). The *outside* of the main trunk was also full of the white flakes. David called it a strange oxidation of some type - he's never seen it before. He researched with friends in the business and no one has ever seen anything like it. It is his belief that all this "oxidation," the white flakes everywhere, started sometime in the last couple of months because he did the annual service and it wasn't there then.

David, meanwhile, has been working for several days replacing all the duct work, installing a new commercial-grade main trunk line that's even wrapped (they use these in hospitals), is going to install a relatively expensive UV light, is spraying even the new ductwork with a special germacide, and he also has had to install a new evaporator coil (he was able to return the old one under warranty).

I have to interject here--David is all about service, I mean you don't find guys like this much anymore. He's doing nearly $5,000 worth of work for $1500. I still can't wrap my head around this.

***This is what I really need ya'll to weigh in on:***

Last night he was showing me the new work in the crawl and he told me that he thinks there's a chemical contamination - he said he's constantly tasting something adverse, much like sucking on a penny. And then I tasted it, having licked my lips, and I was only in there for about 5 minutes. I lead him 6-7 feet away to the cement patio where the bucket of stabilizer and a jug of muriatic acid were. And it hit me. I said you know, there's something vaguely familiar about this taste I have, the penny-in-the-mouth taste, could it be that muriatic acid is leaching out of the jug, through the cap - that the cap is ill-fitting somehow (even though it was not mis-threaded, I checked)? The last time I used the acid was early August, at present the jug is about 9/10th's full. David said, of course acid is incredibly corrosive. In fact, there were even bits of the white stuff on some joists. Could this be the problem? I immediately removed it from the crawl.

Going forward, where to now store pool chems that should be in a cool place? Yes, I do have a quite large and nice pool house, and also a shed next to that, and they are in the lower yard so they would be a tad cooler than the garage, but still very, very hot.

I am so hoping that the problem is the muriatic acid because I want this never to happen again. Next time I would certainly not be so incredibly lucky to pay so little for all this abatement work. David's even going to replace the vapor barrier…