[simonr]

i know the pics aren't good , i thought all the black bits would come off

  before 1
before 2
after 1
after 2

[FRESHER]

Hi Simon,  what strength did you use? What ratio of dilution? Also was it old hypo, or could the hypo be poor quality in the first place?

[Smudger]

What pressure washer do you have pressure and lpm ?
Did you turbo nozzle?

Darran

[simonr]

my sons mate pressure washed it with his £80 karcher a week ago,  its my mums so i thought i'd try hypo on it. got the hypo from an agricultural supplier on saturday,  its red label deosan,
he said he didn't know the strength but to just put a couple of inch in a watering can & rinse down  i left it for 25 mins & rinsed off with hose pipe, i tried scrubbing with a deck brush but it didn't make any difference
there are no % on the label
i read on here about 1 to 7 ratio so i used less than that

[FRESHER]

Sometimes you need two or more applications, I would try 1 to 3 dilution and see how you get on, maybe stronger.   It will be the hypo that gets it off as your farting in the wind using the Karcher. 

[Smudger]

I'd go back and try it neat - the karcher will not have got deep enough into the black spot to leave the "root" exposed for the hypo to get in and kill it.
Your ratio is for light algea removal and general clean down - try 3 to 1 or 2 to 1  (with a good dollop of washing up liquid) delivered by a sprayer this gives better control and holds the hypo onto the surface.

Darran

[simonr]

banging thank you both,
 im talking to ben at rutland about getting my self a pressure washer

cos its my mum's house i saw an op to have a go at trial n error with hypo  and i didn't know about exposing the root

[serj shergill]

[serj shergill]

[serj shergill]

I tend to use neat hypo on severe lichen and then wash it down...

[simonr]

cheers,  got a wall at a mates i might try that on