Grainfather Conical Fermenter Pro - Black residue in fermenter

[leecee]

Hi,

A few weeks ago I splashed out for a Grainfather Conical Fermenter Pro Edition. I cleaned it thoroughly but after the first brew I was shocked to see scum marks inside where the krausen would have been. I've never had this with my Fermentosaurus or when fermenting in corny kegs. I didn't use the dump valve, so for my second brew I scrubbed it clean again and dumped the trub a couple of times. Same again, black stains at a couple of different levels. The fermenter was sealed with a bubbler the whole time.

Anyone got any idea what on earth this is, where it comes from and how to prevent it? The only thing to mention is that the heater was running almost 24x7 to keep the temperature at 18C is my cold garage - But sure the heater is right down in the cone.

Thanks!

 

[Sadfield]

Looks like corrosion. What did you use in your initial clean?

You could try the following.
https://barkeepersfriend.com/cleaning-your-home-brew-supplies/

 

[leecee]

Looks like corrosion. What did you use in your initial clean?

You could try the following.
https://barkeepersfriend.com/cleaning-your-home-brew-supplies/

I used WVP solution that I use for my other kit, thorough rinse, sprayed with starsan. The photo was after the first ever use.

 

[Keith1664mk2]

My stainless conicals did this the first time I used them,It didn't happen again.

 

[borischarlton]

Hey,
Absolutely nothing to worry about, this is krausen residue. It does manifest itself slightly differently on stainless. The colour of it will change depending on how long it has been in the fermenter, how dry it is, yeast choice and grist.
Fill the fermenter with warm water and sodium percarbonate / PBW / Chemclean / OXI and leave for a while, it will then mostly wipe off, you may need to brush or a more vigorous scrub with a cloth if stubborn.

On another note, VWP is not ideal for use on stainless. If left in contact too long it will pit and cause issues.

 

[Sadfield]

So this isn't staining after the krausen residue has been removed?

 

[Alastair70]

Looks like the residue that all new stainless has as part of the manufacturing process. TSP is the best cleaner for stainless but especially the first time, then passivate after cleaning. I use StarSan for that process but citric acid is apparently more effective.
Check out the SsBrewTec knowledge base for more info.

https://ssbrewtech.zendesk.com/hc/en-us/categories/200206485-STAINLESS-CLEANING-AND-CARE

 

[borischarlton]

Looks like the residue that all new stainless has as part of the manufacturing process. TSP is the best cleaner for stainless but especially the first time, then passivate after cleaning. I use StarSan for that process but citric acid is apparently more effective.
Check out the SsBrewTec knowledge base for more info.

https://ssbrewtech.zendesk.com/hc/en-us/categories/200206485-STAINLESS-CLEANING-AND-CARE

The nice thing about Grainfather kit, it doesn't need passivating.

 

[Alastair70]

The nice thing about Grainfather kit, it doesn't need passivating.

I didn’t know that. It’s not an overly onerous part of SSBrewTech ownership, and I then use the starsan to purge a keg, so it’s two jobs done at the one time.

 

[leecee]

Hey,
Absolutely nothing to worry about, this is krausen residue. It does manifest itself slightly differently on stainless. The colour of it will change depending on how long it has been in the fermenter, how dry it is, yeast choice and grist.
Fill the fermenter with warm water and sodium percarbonate / PBW / Chemclean / OXI and leave for a while, it will then mostly wipe off, you may need to brush or a more vigorous scrub with a cloth if stubborn.

On another note, VWP is not ideal for use on stainless. If left in contact too long it will pit and cause issues.

Thanks for that, especially the tip about VWP - I'll get some different cleaner.

 

[Martin O]

I have the grainfather conical and it's normal, it generally just wipes clean sometimes it's a bit stubborn if I have chilled it.

 

[leecee]

So this isn't staining after the krausen residue has been removed?

The photo was taken after taking the beer from the bottom tap, taking the lid off and a quick rinse with cold water. I hadn't given the fermenter a clean with anything. It was more the colour and toughness of the residue that made me panic that something nasty had got in there - But the same happened on the second brew and I made sure it was clean beforehand.

 

[Sadfield]

The photo was taken after taking the beer from the bottom tap, taking the lid off and a quick rinse with cold water. I hadn't given the fermenter a clean with anything. It was more the colour and toughness of the residue that made me panic that something nasty had got in there - But the same happened on the second brew and I made sure it was clean beforehand.

I see. I thought you were worried there was a fault with your new FV and naturally assumed that you'd already cleaned off the krausen residue and that picture was what remained. Thinking you may have removed the stainless chromium oxide layer by using a chlorine based cleaner.

 

[JockyBrewer]

Like @Alastair70 says above, that’s residue from manufacturing - oil and swarf. You’ll get the same on any new stainless steel kit, and I got it with my first grainfather fermenter.

It probably won’t happen again now as the alcohol in your beer has dissolved the oil. When I had this my first beer had a metallic taint to it.

The absolute best way I’ve found to deal with this is to use plain old washing up liquid. Squirt some on generously, then wipe it all over with a damp sponge so everything is nice and foamy, then wash it off with plenty of water until you don’t get any more foam.

Same goes for any stainless equipment - kegs, fermenters, whatever.

 

[jackrussel.terrier]

Anything that contains, or reacts to produce, sodium hypochlorite, is deadly to certain grades of stainless steel, and those grades are often found in things like vacuum flasks. (I once ruined an expensive Stanley flask by weak bleaching- I heard the hiss as the vacuum leaked off!).