OG FG

Strike Water: 72°C
Hold at 66°C to 67°C for 90 minutes

what temperature did you mash at?

it sounds like you mashed at a higher temperature (155-160 F) (68°C - 71°C.) when you mash, there are two types of amylase enzymes active, alpha and beta. the amylase enzymes basically cleave your starch molecules (very large polysaccharides) into shorter saccharide chains to form your sugars in your wort. one of these amylases is more active at lower mash temperatures (149-152 F) (65°C - 67°C) and the other is more active at higher mash temperatures. the one that is more active at lower temps cleaves sugars that yeast easily convert to alcohol, whereas the other one which is more active at higher temps cleaves sugars that yeasts are unable to turn into alcohol.

both types of these sugars contribute to your O.G. however, your F.G. reflects what type of sugars contributed more to your O.G.

in your case, it sounds like you had more high temperature sugars that were unable to be converted to alcohol (gravity ~ 1.00). these sugars will contribute to the mouth feel and body of the beer (which is MUCH more important in my opinion).

that's my take on it. there are also other factors that may be contributing. what is your fermentation temp? fermentation occurs at much lower rates at lower temps. fermentation can continue occurring after 9 days as well! __________________