It all depends on you and your financial situation. You can use a pump up sprayer to apply stains and chemicals. Or you can purchase a 12 volt ac or dc pump along with chemical tubing.
If you use a pump up, you will want to make sure you strain stain before you use it. There is a lot of junk that will get stuck in the tip.
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Dan Flynn
Flynn Service Pro
www.powerwash.net
708/715-4206