Car wash moss and algae or mold (C) D Friedman Car-wash Algae Growth on Cleaning Equipment

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Algae growing in a car wash:

This article describes a problem of algal contamination of the cleaning equipment in a drive-through car-wash. We speculate on the reason that the algae contaminated just this one car wash among a chain of similar facilities and we discuss some solutions for the problem.

This article series describes and provide photographs and microscopic photographs of algae, moss, lichens, or fungal growth that occurs on buildings and in nature. We include links to references useful in the identification of algae, moss, lichens, and mold. Our photo at page top shows moss on an asphalt shingle roof.

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Algae in the Car Wash

Reader Question: How to clean off & prevent moss or green algae/fungal growth in a car wash

Car wash moss and algae or mold (C) D FriedmanHi, I own a car wash. I've been having a moss/algae problem that's becoming progressively worse. The problem is in the car wash tunnel. It began growing on the cloth used to clean the cars and now has spread to some of the steel components and the concrete floor as well.

The Area is very damp, abundant in sunlight, and poorly ventilated overnight when the garage doors are closed.

Originally I had thought my water might be contaminated but I was told that because I have many windows in my tunnel that the sunlight is causing this, while another professional told me it was more likely due to poor ventilation.

I've been in the business for a long time and have had other locations, but never had a problem like this. I'm wondering if you might have any thoughts on what's causing this aside from the dampness factor which I can't help. Any input would be greatly appreciated. I've attached some photos. thank you, E.L. 6/12/2012


A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem with moss, algae, or fungal growth on building surfaces and materials, though I expect you are far more an expert on car wash operation and maintenance than most outside "consultants" you might find.  That said, here are some things to consider:

Some of your photos indeed look to me like moss - I agree, especially along the steel guide track.

But others, on the cloths, may be algae or even a fungus. I couldn't tell for sure from your photo. We could have you take samples and send them to me for analysis to ID for sure what you've got, but because I suspect that the causes and remedies are going to be the same, I'm not sure that step is worth the trouble.

I'll do what I can to assist, pro-bono as long as we can keep the time and writing from becoming too consuming - what we learn will be useful to both of us.

Diagnosis of moss or algae growth in a car wash

Moss, algae, and fungal spores are airborne and are, in a practical sense, everywhere, all the time. So when one or more of these becomes a problem in a car wash it is helpful to ask why here, now and not in other car wash operations? The answer to cause is important in deciding on the cure. Otherwise, you could go to the expense and trouble of a clean-up only to have the problem occur all over again.

Let me pose some questions and perhaps when you see my line of thinking you, knowing the operation well, will think of similar questions to ask or discuss.

Are there significant differences at this car wash from other units you know about in regards to:

1. Water chemistry or water recycling and treatment before re-use

2. Ventilation design and operation. Are your vent fans working, ducts unobstructed, that is, not simply that they run, but do they work?

3. Sun exposure, including near by shade trees, forest, wet areas around your property. It would be lack of sunlight, not presence of sunlight, that would encourage the growth of these substances in the car wash.

4. Cleaning fabric chemistry: the age, duty cycle, fabric used, manufacturer or source or even batch number of the cleaning cloths that show a green growth (algae or moss or fungus or even a combination of all of these?)

5. Rinse water: the cleanliness, temperature, chemistry of rinse water

6. Maintenance: car wash facility cleaning & maintenance schedule or procedures

7. Age: How long has the green growth problem been evident? To my eye, moss like shown in two of your photos does not appear over night or even in a month.

Cleanup & prevention of moss & algae in a car wash facility

I'm not satisfied to just clean the problem surfaces without having a guess at the underlying cause, but nevertheless we can discuss some beginning options.

Steel surfaces with thick mossy growth may need to be hand-scraped as a starting cleanup step.

Use a power washer (with a deck cleaner solution or you may have your own detergent solution) to clean the contaminated surfaces. If you want to salvage and continue using the suspended cleaning cloths, that's a synthetic fabric that should tolerate being removed from the spinner drum, placed on a flat concrete surface, and spray-washed with the power sprayer.

That cleaning won't remove 100% of the moss or algae but it should remove most of it and leave the materials looking clean.

I am doubtful that using bleach or other sanitizers is necessary and also doubtful that it would be long term effective on cloths and on unpainted steel surfaces. If there are painted surfaces nearby that also suffer these growths you might want to use a fungicidal sealant paint the next time those areas are cleaned, dried thoroughly, and then re-painted.

There are also algaecide products intended to be added to pools to prevent algae growth (Utikem and other ammonium chloride based products) but again I'm not sure.

Temporarily you may retard algal growth on the cleaning system by installing UV lighting strategically placed, even if the lighting is left on only at night when the car wash is not in operation. Using UV light to control algae is a suggestion we discuss at STONE SURFACE CLEANING METHODS.

Ultimately you may need to have your water system tested and you may need to adjust its chemistry. Possibly a simple pH adjustment may be all that's needed. Compare the incoming water supply for this car wash with others where the algae problem is not occurring.


Continue reading at ALGAE STAIN TEST METHODS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.




Or see STONE SURFACE CLEANING METHODS for a discussion of the mechanical, chemical, lighting, heat and other methods used to remove algae, lichens, moss, and fungi from stone, masonry, roadways, and other exterior surfaces.

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ALGAE CONTAMINATION at CAR WASH at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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