[UnequivocalBrewing]

I have a dudadiesel plate chiller.  I was setting up to brew yesterday and noticed it had a little grunge coming out of it.  Just looked like it needed to be cleaned. 

So I brought water and PBW up to a high temp and recirculated for ~90 minutes.  It was a murky green almost looked like a diluted motor oil (with hop and grain particles) after the 90 minutes.  I then got clean water and PBW and did the same procedure again.  This time it was a crystal clear green (think listerine) after ~2 hours of recirculating...and it still had some more hop and grain particles in it.

Any ideas what this could be?  Is this the oxidized copper? 

[KellerBrauer]

I’m not familiar with that brand of plate cooler, but if it’s like most plate coolers, the space between plates is extremely narrow.  So, when you add your hops, do you use a hop sack or do you simply dump the hops into the boil kettle?  I have a Blichmann plate cooler and I’ve always used hop sacks.  The cooler is 5 years old, it’s chilled about 50 batches and it’s still in mint condition.  Plate coolers are awesome, but they need to be taken care of with meticulous detail.

I suggest a strong solution of PBW and hot water.  Fill the cooler with the solution and let it sit for a few hours.  Flush it and repeat if necessary.  Yes, it could be oxidized copper and this flushing process should clean it up.  If you suspect the copper is corroded through, I would recommend a LOW PRESSURE (1-2 psi max) pressure test.  Simply cap one wort port and apply pressure with a gauge to the other wort port and watch the gauge. I would use a tire pump to apply pressure.

Hope this information helps.  Good luck!

[mabrungard]

A simple pressure test is to hook up the water hose to the chiller and block the outlet. If water comes out the wort circuit, there is a leak.

I have had green water in my chiller when I made the mistake of storing it with StarSan in it. I’m not sure that an alkaline cleaner can corrode like that. But it is important to occasionally use an alkaline cleaner to remove organic deposits. It is not necessary to do every time, but a good reverse flush after every use, is.

[goose]

I have a dudadiesel plate chiller.  I was setting up to brew yesterday and noticed it had a little grunge coming out of it.  Just looked like it needed to be cleaned. 

So I brought water and PBW up to a high temp and recirculated for ~90 minutes.  It was a murky green almost looked like a diluted motor oil (with hop and grain particles) after the 90 minutes.  I then got clean water and PBW and did the same procedure again.  This time it was a crystal clear green (think listerine) after ~2 hours of recirculating...and it still had some more hop and grain particles in it.

Any ideas what this could be?  Is this the oxidized copper?

I bought a used Dudadiesel plate chiller from a local brewery about a year  or so ago.  It had not been cleaned in quite a while and it took me a couple days of circulating hot caustic through it to clean it up (I used caustic because I had it on hand and it is a stronger cleaning agent).  I ran two caustic cycles and then an acid cycle flushing with hot water after every cycle. Wash, rinse, repeat.  After two days, I finally got it clean.

I had to do the same thing yesterday with a smaller Dudadiesel that one of my brew clubs owns.  We did a 40 gallon batch on Saturday and the previous users of the chiller did not know how to clean it properly.  It had gunk from hop cones and other stuff lodged in it when we were rinsing the chiller before trying to sanitizing and  use it.  We finally had to resort to a back-up counter-flow chiller to cool down the wort.  Three caustic cycles and one acid cycle cleaned it up.  It ran dark brown for the first cycle then went to a green color which was pretty much gone by the end of the last caustic cycle.  Some of the brown color material appeared to be beer stone in the chiller.

Unfortunately, because of the design of the chiller, you can never get every last the particle of hops and trub out of the plates but if you clean it meticulously, there will be very little residue.  I always flush the chiller with hot water in reverse right after I am done chilling the wort and then immediately clean it with PBW.  I also clean it again as a part of the fermenter cleaning and sanitizing process during my brew day.  As other have said, using a hop bag will greatly reduce the amount of hop particles getting into the chiller and keep you from possibly plugging it up.  I also have an inline screen before the chiller to further remove the residue as an additional safety valve.

PBW will work almost as well as caustic for this and is safer to use.  Just be sure to clean the chiller both ways.  You can use either Starsan or Saniclean as an acid wash.  I would mix it at the ratio of 1 ounce per gallon of cold water.  Do not let the sanitizer solution sit in the chiller overnight as it is an acid and could start to corrode the plates.  I know of some breweries that pack their plate chillers with Iodophor after use.  I don't do that at home, I just let it air dry.

Hope this provides some further insight.

[RC]

It's not the copper or any other reaction with metal. An alkaline cleaner, such as PBW or NaOH, plus organic material will always turn liquid various shades of olive-green or brown. It's just a reaction between the alkaline cleaner and organic matter.

As a side note, this is why you should always pasteurize a plate chiller rather than rely on chemical sanitizing. There will always be gunk left in a plate chiller, no matter how much you backflush or chemically clean. I recirculate >180-degree water through mine and when the temp probe at the outlet reads at least 180, I let it recirculate for 10ish minutes. When I begin recirculating, I discard the first gallon or so of hot water because it usually has a very strong butter character to it, presumably from Pedio growing in the chiller in between uses.