A method is provided for inhibiting scale in a liquid hydrocarbon system, including the steps of: providing a liquid hydrocarbon system; providing an aloe-derived scale inhibitor; and mixing the aloe-derived scale inhibitor with the liquid hydrocarbon system in amounts effective to inhibit formation of scale. The scale inhibitor is aloe gel dissolved in water at a concentration of between about 5 and about 50% wt/wt, which includes polysaccharides having a hydrocarbon chain structure having carboxyl and alcohol functional groups that interact with divalent ions.