Stained carboy. Tried everything. Any suggestions?

[Rugrad02]

I have a 6.5 gallon carboy the I have had for 11 years. It has brewed me some great beers but getting it spotless is a pain in the A$$. Recently, I have noticed a splotchy stain that makes up roughly 1/3 of the carboy's bottom. I can see brush marks contained within the stain (Only when bottom is dry) indicating that at some point I have brushed the bottom of the carboy with a carboy brush. I have tried brushing it again but have only managed to leave what appears to be scratches from my carboy brush around the carboy neck. I tried soaking it in PBW, star san, white vinegar, oxyclean, scrubbing with green scratchy pad and a wash cloth, and nothing is working. Anyone have ideas? I've not noticed any infections through 40+ fermentations with it and maybe I'm being a bit obsessive but I would like it stain free. Any other ideas?

Thanks.

 

[day_trippr]

I didn't see bleach on your list. I'd bomb the heck out of it to see what happens.

I acquired a five gallon carboy that had spent at least ten years sitting in a garden as decoration. It had all kinds of nastiness about it, especially hard deposits, but I bleach bombed it for a good week and it now serves as my sparkling clean Star San reservoir...

Cheers!

 

[BigRob]

Have you tried CLR?

 

[AlCophile]

Disclaimer: use this method and materials at your own risk: seek professional help: OK!
At 11yrs old it can't be a PET 'boy, right? Sounds like minerals.....Calcium and Iron salts. See if someone has a small amount of muriatic(hydrochloric) acid. Vinegar is not strong enough.
Be freaking careful, as the actual acid is a gas, dissolved in water, so........acid vapor will leave the solution, and it will do so more as the surrounding temperature increases, like it does in NC in July, and if you inhale it, you may cause lung damage. Be careful opening the bottle!!!
Prepare: eye protection, a breeze or a fan, lots of water to rinse, rubber gloves. A water solution of bicarb of soda would make a wonderful neutralizing rinse, and is safe to use on YOU, should you get splashed. OK for eyes, too.
Put the undiluted acid solution directly on a small area of stain. See if it works....may take a few mins. No hurry, leave overnight.
Rinse, and see if there is any contrast with untreated area.
Btw, seal the 'boy, outside, as the acid vapor will corrode everything it contacts.

 

[BigRob]

I'd try CLR before Muriatic. I've used high molarity Muriatic before on boilers, and it's pretty scary stuff.

 

[Rugrad02]

I tried the CLR this morning and didn't see much of a difference. I did only soak it for the recommended 2 minutes. Is it okay to soak it for longer?

 

[whiteboy87]

I tried the CLR this morning and didn't see much of a difference. I did only soak it for the recommended 2 minutes. Is it okay to soak it for longer?

Is it glass or plastic? Glass would be ok for an extended soak. Not sure what CLR does to plastic, but I would assume it wouldn't be good.

 

[IslandLizard]

On glass I'd scrub it with some Comet. You need some friction/tooth to wear it off.
Use Muriatic Acid as the last resort. As said before, if you're not used to working with strong acids it is very dangerous.

You can leave CLR on it for a few hours, or even days.
It is a household cleaning product and not all that strong or special:

Calcium Lime Rust, more commonly known as CLR, is a household cleaning product used for dissolving stains, such as calcium, lime, and iron oxide deposits.
Its ingredients include water, lactic acid, gluconic acid, lauramine oxide, and Propylene Glycol n-Butyl Ether.[1] The product also contained phosphoric acid at one time, but it is now phosphate-free. The phosphate-free formula is slightly more environmentally friendly, but its effectiveness against some stains such as rust is greatly reduced. (Wikipedia)
​

Are you sure the discoloration is on the inside?

 

[whiteboy87]

Are you sure the discoloration is on the inside?

That would suck if it had been on the outside the whole time!

 

[Rugrad02]

It is a glass carboy. 6.5 gallon. I will try soaking it again for longer. The stain is only on the bottom of the carboy and is definitely on the inside. Should I dilute the CLR at all or use it straight? I have enough to cover the bottom of the carboy if need be. Thanks again.

 

[IslandLizard]

You can probably recover and reuse the CLR after it has done its cleaning. I'd use it straight. It's mostly water anyway

The convex bottom needs quite a bit before it covers the middle part. You could soak a paper towel with it and place that on the stain.

Have you tried Comet (or Soft Scrub) yet?

 

[whiteboy87]

You can probably recover and reuse the CLR after it has done its cleaning. I'd use it straight. It's mostly water anyway

The convex bottom needs quite a bit before it covers the middle part. You could soak a paper towel with it and place that on the stain.

Have you tried Comet (or Soft Scrub) yet?

+1

Try a good soak with CLR and even if it doesn't help you can save it for something around the house. I don't think your mystery stain will impact the effectiveness.

 

[Gitmoe]

I've had great luck with a new cleaner called Super Pro-zyme. Cleans just about anything. Unstained a few of my brew buckets.