Removing Algae from External Observatory Walls?

[glend]

My ROR Observatory has acquired a disgusting layer of algae on the mostly south facing walls. Is there some thing that I can spray on it to kill/clean this stuff? Will a pressure wash alone do the job? TA

[Leo.G]

Pressure washing would be a good start to remove the bulk of it IF the water isn't going to penetrate the observatory and cause damage.
Following that I'd guess most mould killer spray ons would remove the smaller stuff, or white vinegar in a spray bottle, along with most bleaches. Keep in mind bleach and other remedies may kill the growth in the immediate area (grass, vegetation).


https://www.bunnings.com.au/30-seconds-2l-one-step-spray-and-walk-away_p4460169

[leon]

As Leo said 30 seconds will do it use it straight though, and you may need to do it twice than a good pressure clean and it will come up sparkling.

Leon

[Wilso]

Diluted vinegar will kill mould and spores. Spot test first :thumbsup:

[glend]

Thanks folks. Vinegar I have, will try it today.:thumbsup:

[glend]

Well vinegar did not do much, but bleach did. See photo. I will try pressure washer next. That stuff stinks once the bleach is sprayed on it, and it turns into slime.

[glend]

I am happy to report that the "30 second" cleaner from Bunnings works really well on mold and algae removal. :thumbsup: Followed up with the pressure washer to rinse.

[Leo.G]

Algae is always a hit or miss situation depending on how bad it is. A late, former best friend and neighbour would ask me on occasion to go with him to hold a ladder if he was doing high work (he was late 60s). He ran his own house painting business, all across the blue mountains. Many of the houses had mould/algae/heaven knows what on the external walls and I was happy standing there with the pressure washer or his portable steamer if he wanted the old water logged paint gone too. Not so much fun in the rain or winter.
Good luck with the pressure washer!
Depending on the surface you could apply a brush/spray on sealer which would give the algae less grip and perhaps hose off easier. I've heard this mentioned but haven't had anything to do with it. It's probably just called good quality external paint.