Diffusion Stone Clogged?

I am trying to aerate right now with Northern Brewers 2 micron aeration stone. I sanitized the stone (by boiling) on the last batch but didn't end up using it because I didn't have the right size tubing. Now that I do have the right tubing the stone looks a little rusty and doesn't seem to make any visible bubbles or foam. When I put the stone all the way to the bottom of the fermentor the wort actually backs up in the line. I am using the NB in-line filter and an Airmaster 1000 pump that I used when I had an actual aquarium. I would guess that the aquarium pump isn't strong enough to pump air through the stone, but how would you clean the stone to make sure that the stone is open and clear? I am trying vinegar right now, but suggestions would be welcome. I am making NB cream ale (extract kit) today. Cheers.

Didn't your stone come with a regulator? That's what I use with an O2 bottle from the hardware store.

Take off the tubing from your pump and see if you can blow through it with the stone on the end. That will tell you if the stone is clogged or if the pump is too weak. That would also be a good time to start your pump and make sure it's working too. I had to boil my NB stone a couple of times before it unclogged. It's been fine ever since.

Soak it in CLR? But if wort can go up the tube it must be going thru the stone, right?

-OCD

I wonder if you touched the stone? Oils from your fingers will clogged up the "pores" on the stone.

I patterned my aerator after the NB bubbler kit, which doesn't come with a regulator. Just bubbler/filter/stone. I'm thinking that my bubbler is way too weak to force air through this stone, but tell me if your stone got a little rusty, and if that was a concern and how you dried it.

Boil it in PBW. I had to do this once when I let wort dry in it.

Boil it in plain water then blow some CO2 through it. The heat will help soften and dissolve any solidified wort and the CO2 will help clear it. The PBW boil is a good suggestion too. I give mine a long soak in alcohol between uses. Never had a clogging problem after many years of use. I sanitize it with Star San instead of putting it in the boil.

Could also try soaking it overnight in oxyclean. It's pretty good at breaking up organic material. (note, oxyclean is alkaline so don't mix with acids).

You could also mix it with some borox.

the wort actually backs up in the line

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To me this would indicate the stone is fine, but there isn't any air getting down the tube. Maybe you have a leak between the pump and the stone.

^ yes, that is what I was going to suggest. I am guessing you may have a leak at the hose barb on the pump side. It is probably not the barb at the stone because you would have seen the air bubbling out of it.

david_42 said:

To me this would indicate the stone is fine, but there isn't any air getting down the tube.

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Aquarium pumps have different ratings for PSI delivered and how deep they can pump air. My first pump didn't have the pressure needed and precious wort backed up into the tubing. I upgraded to a TetraTec deep water air pump. Solved my problem. only $8.

See link

TetraTec Deep Water Air Pumps @ Q-PET.com

what is pbw. is it plain boiling water

mtgouldbeerda said:

what is pbw. is it plain boiling water

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Powdered Brewery Wash.
A commercial cleaner, sold in LHBS or on-line.
Oxyclean-free is similar enough to use.