We always recommend cleaning first with lukewarm water and a strong, soft brush.
Only then, if necessary, clean with Sprayhood & Tent Shampoo. Most tents, boat covers and sun awnings are perfectly clean by that stage.
If stains and soiling remain visible, you can treat additionally with Power Cleaner. By cleaning in the normal way first, Power Cleaner only has to work on those stains that could not be removed the usual way.
Power Cleaner will work more quickly and effectively this way.