Pressure washer / patio anti moss

hornetstinger

hornetstinger

hornetstinger

Soldato
Joined
6 Sep 2016
Posts
15,649
My back garden is getting pretty slippery, so will be using a pressure washer on the slabs.

What can I do to reduce the amount of moss that grows onto the slabs? Any surface treatment / paint or sealant (that allows the slabs to breath still) or something?
 
If you hired a pressure wash company they would probably use hypochlorite, leave it sit for a while. Then hose it away gently and then pressure wash.

But it is a chemical that needs research to use correctly, if i remember you add a certain ratio to water and spray it on avoiding everything except the floor. Keep away from grass, plants, glass, doors, cars etc.

Use PPE like mask, gloves etc.
 
I give an annual spray of Wet&Forget. Keeps the moss/lichen/algae away and it does work. My driveway butts up against a neighbours and you can see the difference as clear as day between them as they do hee-haw with theirs.
 
yep get a high power bleach V
I've wasted time using a pressure washer when a scrubbing brush and 1:2 diluted bleach a couple of times a year just works.
If you are spraying stuff may need a sprayer with seals which are OK for alkalis.

Jennychem Sodium Hypochlorite Solution 14-15%, Powerful Swimming Pool Chlorine, Patio Cleaner, Transform Your Outdoor Space (5L)
Sold by: Jennychem
Product support window closed on 15 March 2025
£15.50
 
Do not use bleach aka sodium hypochlorite. Any “professional” company using this stuff should be avoided like the plague. Bleach is as nasty a chemical as you can get no matter how diluted it is. It kills absolutely everything it touches.

For domestic use, Wet and Forget is the way to go. It’s much safer and does a far better, longer lasting job than bleach ever will.
 
Wet and forget is BAC, you can get it in higher concentrations for less money elsewhere.

Wet and forget is 10% BAC and about £35 per 5 litre

Generic BAC 50% is £32 per 5 litre.

liquipak-shoponline.co.uk

BAC50 Powerwash Biocide HSE Approved | Outdoor Cleaner for Algae, Mould & Lichen

Shop Liquipak BAC50 Powerwash Biocide in multiples of 5L, an HSE approved outdoor cleaner for algae, mould and lichen on patios, roofs, render, stone and hard surfaces.
liquipak-shoponline.co.uk liquipak-shoponline.co.uk

You mix wet and forget down 4 to 1 so it’s only really 2% BAC when in use.
 
Last edited:
Bluecube said:
Do not use bleach aka sodium hypochlorite. Any “professional” company using this stuff should be avoided like the plague. Bleach is as nasty a chemical as you can get no matter how diluted it is. It kills absolutely everything it touches.

For domestic use, Wet and Forget is the way to go. It’s much safer and does a far better, longer lasting job than bleach ever will.
Click to expand...

Household bleach at 1% concentration is fine and works well.

I put 100ml in a 10l bucket of warm water.

Quick scrub with an outdoor brush

Chuck the remainder on the patio and leave to dry.

The grass it drains onto is fine, and after a couple of days the green tinge in the patio slabs disappears.
 
Like wet and forget, patio magic is also just BAC (7.5%).

Why pay more for a branded chemical? Buy the generic chemical at 5X the concentration for less money.
 
b0rn2sk8 said:
Wet and forget is 10% BAC and about £35 per 5 litre
Click to expand...
wet & forget per above cosh sheet is 1.6% concentration - the dettol stuff I had added to amazon S&S is 1.4% and £14/5L.
not sure why bac50 is called that .. it's not 50% concentration, anyway
e: ie this is what counts in comparison like bleach concentration
fdW665x.png
 
Last edited:
@jpaul please stop.

You have posted the concentration for the ready to use product, not the concentrated version you’d normally buy and dilute 4 to 1 or 5 to 1

Literally from the product I linked above:
  • What is the concentration of Benzalkonium Chloride in BAC 50?
    50%.
Click to expand...

It’s 50%
 
Last edited:
We let winter do it's thing then spring clean the algae which is mainly caused by patio plants in pots, using only water in a pressure washer. This keeps it looking clean and algae free until the next cycle. I try and resist using chemicals where I can.
 
You must log in or register to reply here.
Back
Top Bottom