If you clean a lot of roofs, decks, sidewalks, tennis courts, pool decks and other flat surfaces the Flat Surface Cleaner is the most important tool you will ever purchase.

Because flat surface cleaners are such a valuable tool, everybody makes one.  There is a huge variety of makes and models available.  

Common sizes range from 12" to 36" diameter.  Some have wheels some have brush skirts with no wheels and others have both.  All surface cleaners share a common concept...  spinning nozzles at a constant height from the surface being cleaned.

Some surface cleaners have stainless steel or aluminum housings while the lions share are made from plastic.  Many people tend to think of the stainless or aluminum housings must be the most robust but my experience says the plastic ones are the strongest.  Not only are they lightweight you can drop one off the back of your truck and it bounces back.  Try this with a stainless or aluminum housing and it starts to look like the left front fender of your wife's car. (sorry ladies - just a joke for description sake)  Maybe that's why they stopped making bumpers out of metal! 

When considering the purchase of a flat surface cleaner is the size of your pressure washer, not the size of the surface cleaner.  Many people have been very disappointed when their first job with the biggest, most expensive surface cleaner they could buy looks like crap!  Bigger is better - right.  Well, not with surface cleaners.  If you have a 6.5 HP, 2,5 GPM, 2700 PSI machine and go buy a 36" cleaner with 4 nozzles on 4 arms you will be sadly disappointed.  Check the nozzle chart and you will see how much pressure you will get when you push the 2.5 GPM of water through the 4 nozzles that come with the surface cleaner.

2.5 GPM output divided by 4 nozzles is .625 GPM through each nozzle.  Our nozzle sizing charts don't go down that far but do the math and you will find you get less than 400 PSI from each nozzle.

So, all you have to do is decrease the nozzle size.....  right!  Well this works to a point but let's use the same machine as an example.  Again, it's too small to be on our charts but do the math and to  increase your PSI to 2700 with 2.5 GPM flow you need to install nozzles with a hole size of less than 0.01.  This is 20 times smaller than the nozzles this size machine typically comes with.  The end result would be a nightmare as the nozzle would constantly plug up and the cleaning job would be a mess.

So, make sure you size the surface cleaner to your machine and you will be a lot happier with the results.  In the example above you would need an 8 GPM, 3000 PSI  machine to achieve 3000 PSI from each nozzle.  If you have a 6.5 HP, 2800 PSI pressure washer your on the edge of having good performance.  Look at a 16" surface cleaner with 2 X .020 size nozzles and you will get approx. 2000 PSI from each nozzle.

Diameter is also important when considering a surface cleaner.  Again, bigger is not always better.  Consider that the rotation of the nozzles is done by the force of the water exiting the nozzles.  The more mass and larger diameter  that needs to be turned, the slower the nozzles and the less force there is for cleaning. 

Next, wheels or no wheels?  
Wheels or casters make the unit more easy to move around and allows you to clean outside corners of a raised sidewalk without smashing the rotating arms.  With three wheels on the upper surface you can extend the housing partially out over an edge.  This is very handy.  The downfall with a wheeled surface cleaner is that the casters are a maintenance item.  Expect to have to replace a set of casters occasionally.  They are subject to considerable abuse, being constantly bombarded with dirty water.  Another consideration is wheels or casters.  Some models have large lawnmower type rear wheels, with casters at the front.  They are more for going in straight lines, while casters on all four corners allows you to go in any direction.  Nozzles spend more time in the line of direction, at the sides of the machine compared to going accross the front and back.  So, going in straight lines on long sidewalks can leave lines, which follow the direction your traveling.  I consider the best direction is a figure 8 moving forward.  This is only possible with 4 casters or a floating machine with a brush skirt.

Units with brush skirts and no wheels are great if the pressure washer has enough power to keep it floating.  When the skirt rubs on the ground or dives into the ground on corners they get hard to use.  Brush skirt models are great for cleaning roofs.  Also, when moving over an outside corner, on a raised sidewalk, be careful.  If you go too far the machine will loose lift and fall into the corner, causing serious damage to the nozzles and rotating arm.

BE Pressure make a 2 nozzle 22" convertible plastic machine with a brush skirt and removable casters.  This is the ideal unit for most situations.