Lager issue

I am a beginner I have made 7- 5 gallon batches. I have a fridge set up to lager and made two lager batches so far.

My first lager was a simple Continental Pilsner. It came out good. But the second light lager I did had a strange taste.

I had my teacher, the owner of the local home brew store, try it and said it tasted over carbonated. But it does not act over carbonated. I mean when you open a bottle it does not spray all over the place. I have a braggot I bottled that is like this but after you get it settled down it does not have the strange carbonated taste my lager has.

I used a Brewers Best American light kit and changed the yeast with San Francisco WLP810 yeast. I bottled it the same way I did all my other kits using the priming sugar in the kit. None of my ale kits have this taste.
I steeped .5 lb of crystal 20. And OG was 1.041 and FG was 1.009.
I let is set and go through Diacetyl rest.

The only problem I found was I cooled it down a little to fast and it was slow to start. But I changed the temp and it got going and did fine.

Any idea on what I may have done wrong?

One change I have made lately is I am now using O2 with a stone to oxygenate the wort. when i made this lager i just pored it back and forth to oxygenate.

Thanks,

Bill

You're gonna have to describe the taste to get any help on this.

It has a harsh sharp aftertaste. It is not smooth. More than one person has said it tastes over carbonated.

hope this helps!

Thanks!

Bill

Any more ideas?

A sharp aftertaste can be several things- like overcarbonation. What happens if it's chilled for at least a couple of days before opening.

Same thing. i have let it sit and go flat. it gets better but just a little.

What i do not understand if it is over carbonated why does it not act like it, meaning over flowing when opened.

Thanks!

Bill