Cleaning Fernox stains off concrete drive

[mike004]

Had my radiators replaced yesterday and there are large brown stains (several square metres) on my concrete drive. Near where the old rads were stacked and also where they drained the CH into the house drain.
Tried last night with bleach + water and a stiff brush. But it has not had much effect.
Should I just leave it to the weather? Though god knows when we will get significant rain fall.

 

[Wayners]

Fernox is almost clear.

Rad water can have rust and metals floating in it and it's like an acid. I've seen it strip ceramic glaze when poured down a toilet and bath. Will kill grass as well.
If it's stained concrete I doubt there is much you can do tbh other than clean the best you can

 

[Madrab]

Try Sodium Hypochloride 10-15% in solution, might work.

 

[gas112]

Sika Brick and Patio Acid Based Cleaner - 5L | Wickes.co.uk

Sika Brick and Patio Acid Based Cleaner - 5L

www.wickes.co.uk

 

[mike004]

Gave it a good hard brush over with washing up liquid + hot water, with lots of bubbles. Used a yard brush.
Left it for 10 mins.
Then rinsed and brushed with cold water. Looked promising -- some browny fluid was going drown the drain.
Then we had a surprise thunderstorm, where it p*ssed it down.
Anyway, I'll see how it looks when it is dried out in the morning.
Rads were flushed 6 months ago, so I would expect the sludge content to be low.

 

[mike004]

Try Sodium Hypochloride 10-15% in solution, might work.

Is that the same as domestic bleach? Or stronger stuff?

 

[Fred Blogs]

Is that the same as domestic bleach? Or stronger stuff?

It's just bleach and it stinks but it does work or at least it does for the black mold that seems to accumulate on the outside of walls around here. I just use it neat.

 

[Madrab]

Is that the same as domestic bleach? Or stronger stuff?

It is similar but more of an industrial strength. Used to soft wash buildings/stone/concrete/ render/dashed and coated walls etc.

 

[BS3036]

Domestic bleach is 5% or less; sodium hypochlorite for swimming pools etc tends to be 14-15%. I have used this for killing lichen on a drive with good success (though this is not what you are doing with it). There is also brick cleaner made from hydrochloric acid, but I haven't tried this and it can be a bit tricky to source.

 

[gas112]

. There is also brick cleaner made from hydrochloric acid, but I haven't tried this and it can be a bit tricky to source.

Readily avialable in most diy stores and builders merchants

 

[BS3036]

Readily avialable in most diy stores and builders merchants

True. This 10% stuff seems to be readily available. For stronger concentrations you have to start filling in government forms.