Belgian Dubbel - First brew in almost 2 years!

Today I got reacquainted with brewing! My friend and I brewed a Belgian dubbel and we were pretty excited. The wort ran pretty clear after a bit of recycling, and everything looked and smelled great during the whole process. We ended up stopping the sparge when the runnings were at 1.010, and our post-boil OG was 1.080.

Then I got home and put these figures into promash, and i was a little disappointed to see that the system efficiency turned out to be about 66%. For 12.89 lbs of grain plus 2 lbs of belgian candy sugar, they predicted 1.088 OG for 75% efficiency. I'm not sure what I could do to improve this figure. We treated all of our water with 5.2 stabilizer. Our mash was fairly thin at 1.25 quarts per gallon, and we mashed out slightly low at 164 degrees. It was hard to keep the sparge temperature up high enough when we had to recycle the stuff for a while, but most of our wart volume was the water in the mash, anyway.

We finished up by using pure O2 and by pitching a yeast starter. 3 hours later, we had very slow bubbling, but from what I understand, that's fairly quick activity.

Any tips/pointers for the future for better efficiency?

Do you guys think that the mashout and the sparge temperature was the culprit for the lower-than-expected efficiency? And the slow recycling?

Not a lot of action in the all-grain forum for the past several days... Just curious if I'm correct in assuming that my mashout temperature and sparge temperature were the culprits for my semi-low efficiency? I don't mean to be a pest, but I'm obsessive and I would like to come up with a plan to keep that from happening next time if that will yield better results. Thanks in advance!

You also might want to try crushing the grains more. That should help as will...As long as you hit you OG and FG you shouldn't worry about anything else.

Thanks, I'll try that as well!

Im doing a batch not and I just checked on the hydrometer and accordig to promash I am getting 75% efficiency. My advise is that the lower end of the temperature scale is alright during the mash but be patient. Some people say that 1 hour is all that is needed, but if you spend an extra hour or two and dont push the temperature too high then I think this delivers a better conversion. Also in the sparge I can actually see darker wort when using a sparge arm than when just hosing hot water through the grain bed.