Dwell Time for Vinyl Fence

Good morning! We just accepted our first job for a white vinyl fence. Based on other threads it looks like the fence is treated just like a vinyl house wash. This thread in particular has been very insightful Vinyl fence pricing - #18 by SPC but I am having troubles finding the recommended dwell time? It seems like the mix in that thread was 50/50, but that seems a little hot? That would be about 1% on the wall with our current setup. What would be the recommended percent on the wall, and estimated dwell time? Hoping to plan this all out ahead of time since they have about 800’ of fence.

4000PSI 4GPM Pressure Pro Eagle Belt Drive
Planning to use JROD with 0040/0010/2540/2510 (just ordered have yet to test)

Any other recommendations are welcome. I plan to do a test run of the new nozzles on a buddies house with vinyl siding as well.

There is no mix too hot for a vinyl fence. The only thing with a hot mix is you could burn the grass or plants around the fence. I always DS straight SH on white vinyl fences. I want it to clean up quick so I don’t waste time.

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You can basically make the dwell time whatever you want by the strength of your mix. I like shorter dwell times so I’m not waiting as long to rinse. Although, dwell times can vary depending on what organic substance you’re trying to kill. Rule of thumb is once it turns brown it should rinse it off.


@marinegrunt Somehow that’s the first time I’ve heard the “turn brown” piece. That’s really helpful! To answer your question, it’s just got a ton of algae going on. Very similar to this picture, but worse https://pressurewashingresource.com/community/uploads/default/original/2X/d/d169973d3a712402dca39d5225a3a43f59a25a20.jpg

@Clean_Blue Thank you. I thought I had read that for vinyl too hot of a mix will get discoloration or spotty areas.

Keep an eye out whenever you spray anything organic with SH. It kills it and turns it brown. That’s why you’re able to rinse it away without pressure afterwards. If it’s not brown give it another application of SH before rinsing. It doesn’t matter if it’s green algae or black mildew. It will turn brown.


A house mix of 1% will probably take 1-2 minutes for Black mold to disappear and for green algae to turn brown is about 3-5 minutes. A 50/50 mix would be the max strength I would use for faster results. Not because going straight SH would be too strong but honestly because it’s kinda a waste. The time difference between 50/50 and straight is too minimum for me to justify wasting something that I can dilute and make more mix out of.

Moral of the story, 1-5% strength on a vinyl fence will take anywhere from 1-5 minutes to kill the growth to a point where you can rinse clean.


I washed 1500ft recently…could not get the mix strong enough or dwell time long enough to get the organic off without literally blowing it off with some pressure. Fence was 15yrs old and had never been washed…it was terrible…but it looked like new when done.

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Same, hit it with pretty strong mix and it turned brown but wouldn’t come off without using my jrod HP fan tip.