Algae on walls

aujopimur · 06-02-2016 9:16pm #1

I had the exterior walls dry dashed a few years ago in the hope of avoiding future maintainence, unfortunately it is now covered in reddish/brown crap.
Is there any product to solve this problem, or will end up painting the walls.

dathi · 07-02-2016 1:07pm

aujopimur wrote: »

I had the exterior walls dry dashed a few years ago in the hope of avoiding future maintainence, unfortunately it is now covered in reddish/brown crap.
Is there any product to solve this problem, or will end up painting the walls.

there is no such thing as a maintainence free finish on a house exterior. house hold bleach sprayed on with a cheap weed sprayer will clear it or you can splash the cash and buy an algicide google larsons

dingdong1234567 · 07-02-2016 3:33pm

Sodium hypochlorite (chlorine) diluted down in a napback sprayer. Spray on walls and wash of with hose. It will leave walls like new and lasts for years before you'll have to do it again.

The above can be got at any co-op or agricultural store.

Cerco · 07-02-2016 7:11pm

dingdong1234567 wrote: »

Sodium hypochlorite (chlorine) diluted down in a napback sprayer. Spray on walls and wash of with hose. It will leave walls like new and lasts for years before you'll have to do it again.

The above can be got at any co-op or agricultural store.

In diluting, what ratio would you suggest ?

dingdong1234567 · 07-02-2016 7:27pm

Cerco wrote: »

In diluting, what ratio would you suggest ?

As per manufacturer's instructions. Not my place to advise on dilution ratio chap.

Cerco · 07-02-2016 7:34pm

dingdong1234567 wrote: »

As per manufacturer's instructions. Not my place to advise on dilution ratio chap.

Sorry, I thought you had some experience of using it for the requested application.
Perhaps someone else can assist?
I have used Domestos mixed with water 60/40 , water / bleach. It works pretty well but needs yearly application. If chlorine is better I would be interested in hearing from more about it.

dingdong1234567 · 07-02-2016 7:38pm

Cerco wrote: »

Sorry, I thought you had some experience of using it for the requested application.
Perhaps someone else can assist?
I have used Domestos mixed with water 60/40 , water / bleach. It works pretty well but needs yearly application. If chlorine is better I would be interested in hearing from more about it.

I have experience, just not advising people as to mix ratio on a public forum - QED. Not my place. Talk to any farmer that has a milking parlour, same method of use would apply.

dathi · 08-02-2016 10:42am

dingdong1234567 wrote: »

Sodium hypochlorite (chlorine) diluted down in a napback sprayer. Spray on walls and wash of with hose. It will leave walls like new and lasts for years before you'll have to do it again.

The above can be got at any co-op or agricultural store.

Household bleach is, in general, a solution containing 3–8% sodium hypochlorite and 0.01–0.05% sodium hydroxide; so we are talking about the same stuff. if you are using household bleach mix it 50/50 with water before spraying it on wall

galljga1 · 08-02-2016 10:49am

Sodium Hypochlorite that I buy from a chemical supplier is 14% and will literally burn through most substances so take care when diluting. Household bleach is normally 3-4%, some can be stronger, I guess but I have yet to come across it. To remove algae from sandstone requires a yearly application, it will grow back. Not sure about the red/brown crap you see on some walls.

tommycahir · 18-02-2016 2:56pm

This thread is actually perfect timing as I am looking at the moment on how to get rid of that those red streaks on the gable wall of my house (like ones in this picture) and to clean off all my footpaths which have green algae and black discolouration.

Could I use Sodium hypochlorite as mentioned above or would I be better to use something like algoclear on them?

CJhaughey · 18-02-2016 11:04pm

For footpaths I recommend using granular chlorine, wet the path and sprinkle the grains, use a stiff brush and work them in to the path.
Leave them on for 30min and then hose off.

Stoner · 19-02-2016 7:45am

CJhaughey wrote:

For footpaths I recommend using granular chlorine, wet the path and sprinkle the grains, use a stiff brush and work them in to the path. Leave them on for 30min and then hose off.

Would you know where to get that at a decent price CJ, please

CJhaughey · 19-02-2016 8:26am

Pool suppliers, Chemical suppliers would be two places it should be easily got.

Stoner · 21-02-2016 12:14pm

I'll find out and get back. We suffer from this front and back in the yard and front path .
Recently we had some old cooking vinegar it was well past it's use by date. I poured it on the footpath outside where I have moss, this moss is very slippery in Winter an old person could slip easily.

Anyway where the vinegar landed it killed the moss over night. Obviously you wouldn't put this red vinegar on a wall. But it worked better than Thompson path cleaner.

dathi · 21-02-2016 12:21pm

CJhaughey wrote: »

For footpaths I recommend using granular chlorine, wet the path and sprinkle the grains, use a stiff brush and work them in to the path.
Leave them on for 30min and then hose off.

here is the safety data sheet for granular chlorine please be careful as whent it comes in contact with water it gives off chlorine gas which can cause chronic lung damage
http://www.commercialaquaticsupplies.com/MSDS%20calcium%20hypochlorite.pdf

CJhaughey · 21-02-2016 12:27pm

dathi wrote: »

here is the safety data sheet for granular chlorine please be careful as whent it comes in contact with water it gives off chlorine gas which can cause chronic lung damage
http://www.commercialaquaticsupplies.com/MSDS%20calcium%20hypochlorite.pdf

Point well made however in my experience using it outdoors chlorine gas is generally not as big a problem as it would be when used indoors or a confined space.
But do be careful with it as with any chemicals including bleach.

Balmed Out · 21-02-2016 12:44pm

Just make sure never to mix chlorine and beech. Will produce chlorine gas.

Stoner · 21-02-2016 12:47pm

All good points, it is a DIY forum all the same and we do assume that people are aware of that and will still go about their projects in a safe way, being mindful of the risks and dangers and taking steps to mitigate same, reading labels on containers, double checking, questioning suppliers etc, still a great point about the gasses here, I've heard that before alright well worth highlighting it.

marsbar1 · 25-02-2016 7:45pm

tommycahir wrote: »

This thread is actually perfect timing as I am looking at the moment on how to get rid of that those red streaks on the gable wall of my house (like ones in this picture) and to clean off all my footpaths which have green algae and black discolouration.

Could I use Sodium hypochlorite as mentioned above or would I be better to use something like algoclear on them?

Every day is a school day. I had no idea that red stuff you see all over house walls is algae. I thought it was some kind of red streak or mineral seeping out of the rendering into the paint. It makes sense now.

ianm1234 · 08-04-2018 1:12pm

It's caused by the dye used in render or a high level of iron that was in the sand and is now rusting from moisture, use household bleach then scrub with deck brush and wash off with garden hose not a power washer because you'll pit the render and be back in a few months, then apply a sealer & 2-3 coats of good quality paint

corks finest · 08-04-2018 1:17pm

dingdong1234567 wrote: »

Cerco wrote: »

In diluting, what ratio would you suggest ?

As per manufacturer's instructions. Not my place to advise on dilution ratio chap.

Meowwwwe

dok_golf · 08-04-2018 8:34pm

ianm1234 wrote: »

It's caused by the dye used in render or a high level of iron that was in the sand
No it's not, it's a form of algae.

ianm1234 · 08-04-2018 8:42pm

dok_golf wrote: »

ianm1234 wrote: »

It's caused by the dye used in render or a high level of iron that was in the sand
No it's not, it's a form of algae.

Algae isn't red it's green, it becomes red because of the added colour in render

dok_golf · 08-04-2018 9:53pm

Agreed algae is green but you never mentioned algae at all in your post
http://softwashireland.ie/cleaning-wall-render.php

dok_golf · 08-04-2018 10:06pm

Also , if its caused by dye in the render, how come it thrives on "regular" rendered walls?

ianm1234 · 08-04-2018 10:14pm

dok_golf wrote: »

Also , if its caused by dye in the render, how come it thrives on "regular" rendered walls?

Has plenty of causes, alot of iron in the sand naturally and making it rust, can happen when you have large sap trees by the side of your house or from a pond/lake and it also happens alot with houses near the sea from iron & salt, same as concrete going green with it

dok_golf · 08-04-2018 10:20pm

Making what rust? The red staining ( when caused by algae ) is essentially the green algae shi**ing itself. Its a by product of its' feeding process.

bman1 · 08-04-2018 10:21pm

Mosgo do a product called Green Remover. I've used it. Does exactly what it says it will. Obviously doesn't get rid of dirt. Used it on gable walls that were very bad because they didn't get any sun on them really. Had it all killed off in bout 3 days. They also do a product just for that red algae. But I don't know anything about that, just saw it in the shop.

ianm1234 · 08-04-2018 10:26pm

dok_golf wrote: »

Making what rust? The red staining ( when caused by algae ) is essentially the green algae shi**ing itself. Its a by product of its' feeding process.

It makes iron in the sand rust which can stain the wall,

dok_golf · 08-04-2018 10:27pm

The best one I've used is Owatrol ATM 007. Kills all moss, mould, algae and doesn't discolour the walls

dok_golf · 08-04-2018 10:28pm

ianm1234 wrote: »

It makes iron in the sand rust which can stain the wall,

Sorry, but it doesn't. The only thing that can make iron rust is oxidisation

Rust is an iron oxide, a usually red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture. Several forms of rust are distinguishable both visually and by spectroscopy, and form under different circumstances. Rust consists of hydrated iron(III) oxides Fe2O.

Algae on walls

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