How To Best Clean Your Tarmacadam & Cement Walkways

Wooden Patio decks (including those pressure treated), Stone Patio’s, Tarmacadam and Cement Walkways can, each surface combined, attract mildew, algae, lichen, liverwort or cyanobacteria called Nostoc. Same is wholly encouraged by our persistent damp, humid, shady conditions, our clean air and more often poor drainage. So how do we rid ourselves of this constant occurring problem?

Many people use washing powder to kill off this growth, spreading it over the offending surface. Same washing powder does work, killing the moss, but leaves behind a brown deceased moss skeleton, which is never easy to shift and if left behind can become slippery, for those not so steady on their trotters.

There is however another product which better solves this algae problem. Its name is Chloras, a product used by Dairy farmers for cleaning and flushing out milking machines.

Chloras is a bleach, so users are required to take care, as the product is extremely strong. Bleach can damage your clothing and footwear if unnecessarily splashed about. It is therefore advisable to use your Wellington boots, your old overalls, plastic gloves and more importantly, wear good eye protection by way of goggles or safety glasses. Remember bleach is never recommended for use near plants and can discolour certain types of stone.
Important Note: Try also to keep your domestic pet off any treated area for a day or two, as the bleach could potentially burn their paws, causing the animal some mild discomfort.

To obtain a quick clean using Chloras, use one-part bleach to ten-parts of water. Same can be spread / sprayed using a watering can with a rose nozzle fitting or a knapsack sprayer. Let the solution sit on the affected surface area for some twenty minutes, before rinsing off, using a yard brush and your garden hose.

Chloras not only kills off all algae, but also the spores present, thus slowing the return of such growth the following year. Used on cemented areas, the surface will be returned to its initial fresh greyish colour.

Chloras is readily available here in Thurles, Co. Tipperary from Centenary Co-Ops Meal Store and Fuel Section, situated on the Templemore Road, at Monacocka, Thurles.


13 comments to How To Best Clean Your Tarmacadam & Cement Walkways

  • Michael

    Great News George. Centenary Co-Op will Be Busy.

  • Rob

    Be careful using in on tarmac as it can stain the tarmac.

  • George Willoughby

    It can indeed stain tarmac, but only if the concentration used is less than 1 one part solution to 10 parts water. However, the Moss / Algae is a tarmac problem also. Products used to repaint tarmac are easily available, and necessary to the maintenance of tarmac anyway.

  • Norman Smyth


    Is Chloros harmful to plants or grass? I have a patio that I need to clean which is bordered by shrubs and grasses. If I spray with Chloros diluted at 4:1 and then power wash will it harm the soil or plants?

  • George Willoughby

    From my understanding, bleach cleaner does not harm grass or plants when used as directed. The company, however suggests rinsing grass and plants with water from your garden hose, if the product comes in direct contact with bleach. This prevents short time scorching. Personally I have never used the product near grass or plants; only in relation to moss on stone paths. Ratio I used was 9 to 1.

  • Sinead H

    If this is used in a 1:10 ratio is it okay to use on tarmac without staining/discolouring it?

  • George Willoughby

    Best for tarmac is simply cheap washing powder. Sprinkle powder over the affected area preferably on a wet day. Moss will be killed off and can be swept away after a few days.

  • M

    Does it remove red algae from walls ? What ratio would you use for this ? Thanks

  • George Willoughby

    Have never used it on red algae. Remember it is an acid and difficult to apply to perpendicular walls without skin and clothing being splashed. Best and cheapest in long run to power-hose and paint.

  • Katie

    George. A complete different ask. I am inundated with request’s as to the following…It’s all over our news here.
    Is Megan Markel taking the place of Irish Maureen O’Hara in a movie. I hope this is an April fools day joke. But one of our Irish seniors said he read it on the Irish paper. Any idea George. I can’t see it myself.
    I have a lovely china doll of Maureen dressed in her beautiful Green silk outfit, like she had on in gone with the wind. I have her about 30 years,

    Thank you George.

  • George Willoughby

    I think you are mixing up Maureen O’Hara with Scarlet O’Hara. Your Maureen O’Hara doll is possibly from “The Quiet Man” era. Either way Megan Markel will never take her place, she does not have the same ability as an actress.

  • George Willoughby

    Katie a check indicates that this satement is indeed an April Fool joke. [The film is due for release on April’s Fools Day 2023.]
    See link
    The article says

    “ Gerard Butler, whose role — and accent — as an Irish man in PS I Love You captured hearts across the Emerald Isle.”

    Gerard Butler is a great actor but his Irish accent in this movie was far from great. Definitely an April Fool. So no need to worry.

  • Katie

    Thank you George. I am so glad this was an April Fools
    Day joke. Sean is one Irish senior very concerned about this. I will now cheer him up with your good news. He had the Covid injection. Wonder if that had anything to do with it. HA HA. He is very much into Irish History. Must say there are times I don’t have a clue what he is talking about. Thank you once again George.

    Stay save. Numbers up again in Ireland.


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