Killing Green Growth

[Old-Guy]

It's been such a wet summer that green algal growth and even moss can be seen growing on lots of cars. Round the sunroof, along seals - anywhere in good light where a bit of water stays trapped. I know from past experience how difficult it is to get it off seals especially the 'brush' round the sunroof - inspiration struck this summer when cleaning a patio using Patio Magic (it really is magic stuff if you follow the instructions).

I saved the last egg-cupful from the sprayer and carefully painted some around the sunroof (I masked off the roof in case the solution marked the paint). After a couple of dry days, the green had gone black. After a few weeks, on a drizzly day I gently scrubbed away all the dead remains with a soft toothbrush - even from the inside edges of the bottom window seals. I don't know what nasty algicide is in Patio Magic, but it works a treat - after a pressure wash, it keeps a patio growth free for about a year so hopefully the car will only need doing every year or two.

The down side? It about £10 for 2.5L of concentrate - enough to do a decent-sized patio or about 1,000 cars!

Use disposable gloves!

[Gibbo2286]

You might have had the same results by simply laying a length of zinc coated cable (the stuff they used to support tv aerials) around the offending parts for an hour while it was raining. The zinc leaches out and kills the fungi. Works fine on a mossy shed or house roof too.

[Peter.N.]

De ionised water as used by window cleaners is very good at getting rid of it, it is on window frames anyway.

Peter

[Old-Guy]

De ionised water as used by window cleaners is very good at getting rid of it, it is on window frames anyway.

Peter

It's too much soft water (rain!) that enables the algae to grow. Window cleaners probably use de-ionised water because it doesn't leave any water stains when it dries.

I've tried all sorts of ways to remove algae in the past (but not galvanised wire (zinc) - thanks for the tip!) - the problem is that once established, algae eats into the surface (sort of micro-roots) and is impossible to 'wash' away unless you can actually kill it so that it decays.

[Spaces]

I find a pressure washer is the easiest method, I use a friend's industrial quality one - better than many sales of cheap domestic ones which invariably fail prematurely. Just watch out you don't start removing paint lacquer - make sure it is cold water.

[Peter.N.]

De ionised water as used by window cleaners is very good at getting rid of it, it is on window frames anyway.

Peter

It's too much soft water (rain!) that enables the algae to grow. Window cleaners probably use de-ionised water because it doesn't leave any water stains when it dries.

I've tried all sorts of ways to remove algae in the past (but not galvanised wire (zinc) - thanks for the tip!) - the problem is that once established, algae eats into the surface (sort of micro-roots) and is impossible to 'wash' away unless you can actually kill it so that it decays.

Its also very aggressive toward accumulated dirt, I wouldn't have believed the effect it has until I saw my son using it (he is a window cleaner). Because water has an affinity for most types of particles, i.e. rain drops are formed around dust, if you remove virtually all of them as does reverse osmosis and de ionising, it attracts all the particles it can get to, when cleaning windows for the first time with it all the muck comes out of the gaps and joints which makes it hard work but the next time its much easier. It cleans the green off north facing walls like lightening.

Peter

[isisalar]

That's very interesting re the de ionised water. I can't see it killing anything though.
In the course of my work I frequently have to kill/ remove black mould from bathrooms or water damaged walls and there is nothing better in my opinion than HG mould spray. It comes in 0.5ltr spray bottles for about £6. Follow the instructions and be amazed.
Left too long on a painted timber window sill,for example, it will start lifting the paint sometimes, be careful and test it on an inconspicuous area. I'm pretty sure it would be ok on car paintwork. Its fine on bath enamel and upvc windows, has quite a strong bleaching action.
Kind regards
Paul

[Peter.N.]

I agree, I don't suppose it will kill anything as its only water, but it does seem to have a very aggressive detergent effect.

Peter

[CitroJim]

How about using dilute bleach?

[Old-Guy]

I tried a fairly strong bleach solution on the patio and drive (far stronger than I'd dare use on the car!) it just turned the the green growth brown and it was still stuck fast, and a few weeks later it was growing as well as before. The algicide in Patio Magic at a low concentration (IIRC the 'concentrate' is 5%, which is then diluted to 1% before application) poisons the algae killing it off completely so that even its 'micro-roots' disintegrate within a couple of weeks.

There's nothing magic about de-ionised water, it is pure soft water just like rain water or distilled water but made by a chemical process of ion-exchange to remove the dissolved mineral salts rather than by natural (rain) or artificial distillation.