Stainless steel and bleach don't play well together

cwuffman

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LifeTime Supporter
Jun 27, 2012
66
The Woodlands, TX
I am not sure where this post best fits, so please move it to where it best fits.

Over the summer I automated my bleach addition with the use of a Stenner pump. It was a great success.

I thought it would be nice to have level indicator on the outside of my 15 gal carboy, so I got a piece of transparent 3/8" tubing. To weigh the end down in the carboy I used a piece of scrap 1/4" 316 SS tubing with a 90 degree fitting on the end which I pushed into the submerged end of the plastic tubing. The tubing was then dropped down into the bleach to fill. I plugged the other end and pulled out a loop to reach the bottom of the vessel and back up to the top again. After unplugging the end, the level on the vented end receded to match the level in the vessel. Success!

Worked fine for a few days. Then I noticed that that it wasn't working any more. I figured somehow air had gotten in and I would just have to refill the tube and start over.

I wasn't in any hurry to correct the situation so it remained like this for possibly a couple of weeks. When I finally pulled out the assembly, I found the stainless steel to be covered and plugged with black gunk. So I left it out and decided to come up with a new plan.

About this time was when 6% bleach was replaced by 8.25%. And I also got better pricing by using some 10%. What seemed to happen was even though I was increasing my chlorine strength, I was having to continually increase my injection pump time more and more to provide enough chlorination, up to an hour longer than I had previously injected 6%. Something was VERY strange.

Finally when the level in the carboy was getting close to the bottom I shined a flashlight in to discover a significant layer of black gunk in the bottom of the barrel. I dumped the last couple of gallons into a white bucket. It resembled dark black/brown muddy water. Apparently whatever the SS tubing did to the bleach hadn't stopped when I removed it from the barrel. It was still severely reducing the effectiveness of the remaining and additional bleach.

I rinsed the carboy and refilled with new 8.25% bleach and things are back to normal.

The moral of this rather long story is that chlorine bleach is very corrosive and you must be very careful about what materials you use when you automate. I think I read on a previous post that someone had installed a stainless steel valve in conjunction with a Liquidator installation. I am guessing that that was probably not a good idea.
 
Good info, thanks! I finally got around to getting my pump and 15 gal carboy and will be installing in the next week or two. Have you found any 10% chlorine in the Houston area? I have seen some at Warehouse Pools and the equilivant price comes out to about equal to the 8.25% that I can buy anywhere else. I am looking for somewhere that I can buy it in bulk (5 or 10 gallons) and reuse the same container.

Thanks.
 
I haven't found any price better than 4 gallons 10% for $14.99. Since bleach went from 6% to 8.25% the price of cheap bleach is not much better than "liquid chlorine" from the pool stores. The bleach distributers took the opportunity to save by shipping less water AND increase the absolute price at the same time. We'll just have to keep our eyes open. I keep a spread sheet with calculations based on current pricing to try to keep ahead of the game.
 
I'm also in the Houston area and interested in the liquid chlorine prices, and the stenner pump setups as I also plan to install one. You guys mind posting pictures of your stenner setups? I'm sure everyone, including myself is interested. Leslie's near me doesn't deal with liquid chlorine at all, so I'm just grabbing 8.25 at walmart or target.

Best,

Paul
 
I'll post pictures of my setup when I get it done, I plan on installing just like Carl did, it seems to be a very clean installation and keeps the tablet feeder in the system in case it is ever needed in the future.

I've attached the excel spreadsheet that I use for you to look at. I've only found the 10% at Warehouse pool supply at a price of 4 gallons for $14.99. The price is pretty much the same as the cost of the store brand 8.25% bleach. I am looking for a local supplier that would sell it in bulk so I can buy 5-10 gallons at a time and not have as many bottles around.

Steve
 

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Guys - we kind of drifted from the original topic. I'm still a bit lost as to how this minor immersion of steel would have caused this. I have seen rust and other things cause some problems but Richard (chem geek) and I talked about it and it's not a self-sustaining thing - once the metal is removed it's not going to have a permanent impact - at least that's what I understood.
 
As I understand it after consulting with some of the chemists where I work, the action of the chlorine on the stainless steel produced byproducts which continued to reduce the strength of the liquid chlorine even after I removed the source. That was the layer of gunk I found several weeks after taking out the tubing. So perhaps there would have come a time when the addition of new "bleach" would have neutralized these byproducts as well. But once I discovered the "gunk" it was just easier to remove it, clean out the carboy and start over. Anyway, it's working great now.
 
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