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Yellow staining after spraying a roof.

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I recently had the experience where I sprayed a roof with the "quick apple sauce" and the algae changed from dark to yellowish.  Am I expecting too much too soon?

 

I'm still very new at this no-pressure roof cleaning, and get hinky when a roof doesn't look clean when I leave a site.

 

Please help.

 

Thanx.

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I had this same question when this first happened to me. I mostly have this problem with shingle roofs. All you have to do is spray the roof again. Usually it takes 3 coats if its really dark to get it completely clean. On occasion I've also had to rinse the roof because it can leave an orange tint behind. I put in some pics as an example to what you're describing.

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20 sh 30 h2o, supplier goes through 1500gal a week, not weak mix or sh. I've never had any black roof come clean with just one application. At least two coats and some touchup spots after that. You could spray straight sh if you wanted a stronger mix but I wont. It will not clean up with a couple good rains if the roof is left looking like picture #4 above because you haven't completely killed all of the GM. All the black is gone when I leave also... picture #5.

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At that ratio the mix should foam up and start working immediately but I give it minimum 10 mins; 15 if shady or cool (don't usually have that in s fl). By the time I spray the whole roof I can go back to where I started and repeat. I did a shingle roof last week that was completely soaked from the rain as I was setting up equipment and it still worked as normal.

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Thanx for the help guys.  I use the 2:3 ratio.  How much time is normal between applications?  Minutes, Hours, Days?

 

Thanx also for the encouragement.  I'm not alone.

I always use 20 gallons of fresh SH with 40 gallons of h2o. Roughly 33% SH

Very easy to do the math. whatever amount of SH I use i add double the water. If im running low during a cleaning i can easily add more to the tank without changing the strength.

 

For me the yellow lichen is the worse and we have lots of it! takes a few application and some waiting for it to whiten up. The heavy black algae stains take a few coats also. The roofs are clean when we leave and we dont rinse. If it looks similar to picture 4 above then it needs another application.

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I always use 20 gallons of fresh SH with 40 gallons of h2o. Roughly 33% SH

Very easy to do the math. whatever amount of SH I use i add double the water. If im running low during a cleaning i can easily add more to the tank without changing the strength.

 

For me the yellow lichen is the worse and we have lots of it! takes a few application and some waiting for it to whiten up. The heavy black algae stains take a few coats also. The roofs are clean when we leave and we dont rinse. If it looks similar to picture 4 above then it needs another application.

Always remember, the mix is Yellow, and shows up on a light colored roof when it dries.

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20 sh 30 h2o, supplier goes through 1500gal a week, not weak mix or sh. I've never had any black roof come clean with just one application. At least two coats and some touchup spots after that. You could spray straight sh if you wanted a stronger mix but I wont. It will not clean up with a couple good rains if the roof is left looking like picture #4 above because you haven't completely killed all of the GM. All the black is gone when I leave also... picture #5.

I get mine in one good heavy coat. Always check afterwards. 

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I remember as a kid a that my dad used to bring home retired work motivational posters, and one read "Measure twice, Cut once."  My new maxim, when it comes to roof cleaning is, "Inspect twice, set your ladder ONCE."

 

Thanx for all the help on this guys.  Have a great summer.

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I remember as a kid a that my dad used to bring home retired work motivational posters, and one read "Measure twice, Cut once."  My new maxim, when it comes to roof cleaning is, "Inspect twice, set your ladder ONCE."

 

Thanx for all the help on this guys.  Have a great summer.

LOL, "rinse well, replace plants never" :)

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