What is this on my Fernox TF1 filter ?

[shd1970]

I have a Fernox TF1 fitted on my central heating system
Boiler is a Worcester Bosch Greenstar 37cdi

There was a slight drip from the lid of the filter so i took it off to put some PTFE on the thread and took the opportunity to clean the filter
It has had a drip for some time and has had to be topped up a few times
I last cleaned it around 12 months ago and the best description of what i cleaned off the filter was like melted chocolate in colour and consistency but this time, it was completely different (see picture)
As per the picture, it was black and almost like metal fillings !

Based on that i have had to top up the system a few times, would this indicate that the inhibitor has now become so diluted that the deposits i am seeing is effectively rust ?

Can anyone advise, what do i need to do please......clean the system and then re-fill and put another can of inhibitor in ?
If it needs cleaning, do i need to use any particular product or should i just empty and use clean water ?

Also, what damage has it likely done if any ?

Many thanks in advance

 

[Dan Robinson]

It's the inside of the rads rotting.

Why did you put PTFE on the lid thread?

 

[shd1970]

There was a drip from the top of the Fernox Tf1 hence why i ran a few rounds of PTFE around the thread
That looks to have been the reason for needing to top up the system as i took a reading and it doesn't appear to have lost anything since

 

[shd1970]

has anyone got any advice on my other questions please, namely :

1. do i need to flush the system
2. is there a cleaning fluid i should run through the system first before adding inhibitor again and if so, are there any recommendations ?

thanks in advance

 

[oilboffin]

System should have been flushed before fitting boiler get a flush done then get a couple of shots of inhibitor in the system and after a year give it another shot and hope for the best.Bob