My own aeration oxygenation problems

I hate to beat this to death but its driving me nuts. I did 2 batches of stout and used my new williams O2 aeration kit on both, one was a sweet stout and the other a Guinness clone 6 lb 2-row 2 lb flaked and 1 lb roasted, and a little acidulated, the first batch was aerated for about 1 minute with 02 per williams instructions, and stopped @ 1.026. the guinness clone was aerated for about 2 minutes and stopped @ 1.025. The sweet stout used british white labs with starter, and the guinness clone used a Irish white labs with starter.
Last tuesday I made a Murphys clone, same as the guinness minus the acid malt. I didn't have any DME so no starter. Irish ale yeast white labs. I DIDN'T aerate with 02, just let it splash while racking from the brewpot, took a reading today 5 days and its @ 1.012 started @ 1.044, attenuated fine, so what gives. i'm very leary of the 02 now. The only difference between the 2 dry stouts was a starter and 02 aeration, any ideas fellas, bad 02 tank, not enough time?
Tuesday I'll do both methods of aeration the splashing and the 02, and if it stops short I'll assume the 02 tank is bad if there is such a thing!!!!
Thanks guys I appreciate the help in advance.

Were you using the yeast cake from the Guinness clone for the Murphy's clone? That could account for the higher attentuation...I assume when you say 'stopped' you mean naturally quit fermenting, given time, not stabilized. I have found that for dry stouts, even Guinness style, although it may seem obtuse, London yeast works better than the Irish. Higher attenuation. :rockin:

No cake, a fresh vial of irish ale yeast. Yup I meant quit fermenting.

Did you shake up your fermenter immediately after aerating with O2? It is a good idea to do this so that the oxygen gets dissolved evenly throughout the wort, particularly for heavier beers like stout. You don't need to shake much -- just enough to swirl things around a bit and get everything mixed in well. I actually do this two or three times WHILE I am oxygenating.

Thanks i'll give it a try, but all 3 stouts were not very high starting gravity, especially the 2 dry stouts.

Did your starter take off well and did you oxygenate it? I'm beginning to think I would NOT want to oxygenate the batch if your starter was fully churning. Your cell count would be fine for full attenuation at that point.

How do you know it quit fermenting? If you judged this by lack of airlock activity, this is not a reliable method. An hydrometer is reliable, and you can assume that fermentation has stopped if there is no change in gravity over a period of at least two days. At this time of year, my brews take about 4 - 6 weeks to ferment out. (I'm too cheap to heat the house when there's nobody there, and lower temperatures meen slower fermentation.)

-a.

My house temp is @ 68 degrees and I took gravity readings starting on day 8 for one week with no change, this has never happened before and I've brewed at least 4 other beers this winter. I oxygenated the starter and it took off pretty quick. As per White labs web site (for british and irish high flocculation)I even tried to stir it and resuspend the yeast and a week later still no change