Cleaning lichen off patio

Squid Vicious · 9 Feb 2018 at 09:55

Any suggestions on how to remove lichen from the patio (the moss I can easily remove with a bit good old fashioned elbow grease)

I've tried one chemical product which was supposed to kill lichen but it seemed to have little to no effect. Any other chemical products you know that work?

Would a 130 bar pressure washer be powerful enough to clean things up? (looking at the titan brand thing from screwfix)

samcat · 9 Feb 2018 at 10:21

I have always used water/bleach 50:50 mix. Hot dry weather ideally, but at this time of year you want dry day or two, and plan to do it properly in the summer. Apply liberally, let it sit for a bit, course broom and work it in. Apply some more, let it air dry. After a couple of days wash it off (hosepipe). Now pressure wash, once this has been done repeat the bleach:water mix process above. Kills all the spores and helps get it up.

Works for me, am sure there are products you can get to do it. Dont make my first attempt mistake years ago and use weedkiller.. It didnt work, but it did kill ALL the grass near the patio and path... :/ Boy I felt stupid!

Rotty · 9 Feb 2018 at 10:49

I use bleach too

Squid Vicious · 9 Feb 2018 at 10:56

Thanks for the tips guys - will wait until weather improves and get some bleach onto it.

samcat · 9 Feb 2018 at 11:00

Squid Vicious said:
Thanks for the tips guys - will wait until weather improves and get some bleach onto it.

Hot and dry is the best, it sucks up the water/bleach mix which then kills it.

robj20 · 9 Feb 2018 at 12:04

Or even better caustic soda.

balls · 9 Feb 2018 at 13:23

I've always just used a pressue washer on mine. Previously had a Nilfisk c110 which took a while,but did the job, and newer p140 does it considerably quicker

m4rmite · 9 Feb 2018 at 19:56

always wet the slabs first or they suck up the bleach and doesn't have the desired effect

Kaka · 9 Feb 2018 at 23:32

For really badly affected paving with lichen, I've had to jet wash and then apply a solution of commercial grade bleach (15% sodium hypochlorite).

m4rmite · 10 Feb 2018 at 05:36

Kaka said:
For really badly affected paving with lichen, I've had to jet wash and then apply a solution of commercial grade bleach (15% sodium hypochlorite).

At work we use a mix of sodium hypochlorite and caustic soda liquor to kill the bacteria in our scrubber system, this stops legonella from forming in the water.
Interesting fact about caustic soda liquor (sodium hydroxide), its strength is measured in "twaddle" :rolleyes:

NickK · 10 Feb 2018 at 11:57

Patio Magic. Put on leave for a few days then power wash. I use just a the low model K2 with the patio spinner top then use the second lance on the tough bits: https://www.screwfix.com/p/karcher-full-control-k2-home-110bar-pressure-washer-1-4kw-240v/7105t

The circular head scorers harder than the variable power lance and then the second lance really scours harder than both.

encephalopathy · 11 Feb 2018 at 22:00

i use the local farming supply place to buy a large barrel of hypochlorite they use on milking parlour floors to clean them. Pre spray the flagstones with water then brush it in almost neat, leave for 30 mins then rinse off- you can see it reacting with lichen and bubbling

Squid Vicious · 18 Feb 2018 at 17:15

I picked up the pressure washer and was giving it a little test this weekend (no chems involved yet) and it does it a great job of cleaning all the muck, moss and lichen off BUT.... the flow rate or pressure from the outside tap is a little lacking - I've tried connecting with both standard garden pipe and a 'magic' hose (kink-free extending thing - great for watering the veg) but the end result is high pressure for 30-45 seconds before it drops off and I need to wait for similar amount of time before I can blast off another couple of bricks.

Options...
1) Call out the plumber and see if they can do some magic with the outside tap (flow does seem to lack in comparison with the indoor taps)
2) Connect the hose to the mixer tap in the kitchen using any one of a number of connector devices but risk a soggy kitchen should it slip or otherwise leak - though have noticed that there's an aerator that screws in so could provide a secure method for securing a connector
3) Looking under the sink I can see that the hose for the washing machine connects to what appears to be 1" male connector with valve

Kaka · 18 Feb 2018 at 18:41

Certain pressure washers can draw water rather than rely on it being force fed, so perhaps a water butt or a container might work.

Squid Vicious · 26 Feb 2018 at 12:02

I picked up a hozelock 2304 9000 with adaptor for 22mm external thread - goes onto the kitchen tap nicely and now I have sufficient flow to keep the pressure washer going at full power.

Just need to wait for some decent weather now... and some fine sand to replace the stuff that gets blasted out from the between the blocks.