Roof Cleaner: Full Coverage

Beware competitors quoting a range of coverage. (for example 500-1000 sq ft. )

Does the product work the same at 500 sq ft as 1000 sq ft?
What is the strength of the product at 500? or 1000?
If 500 sq ft is the full strength coverage.... then using the product to cover 1000 sq ft, makes it 1/2 as effective.

If 1000 sq ft is the full strength coverage... then using the product for 500 sq ft, make it 100% too strong. So why do companies give a range of coverage?

It makes the price SEEM lower.
When you see a range, always pick the lowest coverage as the real coverage.
When you pick the higher coverage, the product will only work 1/2 as well.

Liquids also play games...
Always look at the number of gallons the diluted product makes.
Some products claim that 1 gallon covers 500sq ft of roof.  
You try it spreading a gallon that thin!
On a good day 1 gallon covers 250sq ft.   1/2 of their claim.

(Cleaner Today calculates 1 gallon = 187 sq ft coverage,
 that way you have plenty of cleaner,
 they claim you can spread 1 gallon over 3 times as much space)

Confusing... isn't it!

Cleaner Today's only quotes a single coverage, at FULL STRENGTH.