What strength of melatonin to treat acid reflux gerd and when will i start to notice a difference?

Not the best: drug for treating that. Drugs for acid secretion or changing motility are better. 6 mg. http://www.medscape.com/viewarticle/717460_5

Higher doses: On the order of 5-10 mg daily were used in several studies regarding melatonin and GERD. Remember, some of these studies involved other B vitamin supplementation too. Several studies have reported significant symptoms improvement by 7 days of supplementation.

Melatonin-GERD: Melatonin – Melatonin, a hormone that helps to control our body clock, has been shown in studies to help protect the lining of the stomach and to increase the pressure of the lower esophageal sphincter, which helps lock acid out of the esophagus. Try 3 mg of melatonin two hours before bedtime for up to four weeks.