Fernox F3 versus Fernox F8

[Bogart]

Had F3 going around my system for some time now. Cutting some pipework yesterday found pipe still sludgy inside. Would it be worth trying F8 as supposedly stronger?

 

[Chuck]

Had F3 going around my system for some time now. Cutting some pipework yesterday found pipe still sludgy inside. Would it be worth trying F8 as supposedly stronger?

IIRC, Fernox recommend a second drain-dose-flush cycle with F3 for systems that have a lot of sludge to dispose of.

 

[Bogart]

Have got a few bottles hanging about so will dump them in there and let it slosh about for a few days. I would consider a powerfush but not connected to a foul drain.