Brown/Black coming from Heat Exchanger

[pinheadplanet]

Hi
Moving on from a previous post today, I'm now cleaning out my HE with Fernox DS3 and after my first solution drain this is what came out

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• pinheadplanet
• 11 Nov 2013
• 1

as you might see the stuff coming out is black/brown.

I was guessing the HE was blocked with Limescale build up as we live in a hard water area but that's not what I think limescale would look like...

Should I be doing anything else? Using another product? DS3 is for limescale...

Any input would be appreciated, as always.

THANKS