All grain Lager fermentation issue

Hi all,
I brewed a 53L lager (all grains) on Tuesday 27th May. It was a simple Pilsner recipe with moderate OG of 1046. I use a refractometer to measure the gravity, and this checks fine on water.
I used 2 x bohemian wyeast smack packs (the dates on the yeast were approximately 6 weeks old) and I made starters with both of them (using a stir plate) - 1 litre each.
The fermentation seemed ok to start with and it ramped down to 1022 by Friday 30 May. However since this date, its remained the same.
The FV SP was set at 12.2C with and looking at my trend data this didn't budge by any more than 0.1C.
I tried to shake the FV to get the yeast moving again but no joy on Thursday 5 June.
In a desperate measure on Saturday 7 June I rehydrated some Saflager S-23 yeast to see if the issues were with the yeast. Again this made no impact to the fermentation so on Sunday 8 June I ended up aerating the wort/beer mix again for 5 minutes using a pump and stone.
Anyway, Ive checked yesterday and today and theres no movement at all.
I have no idea what to try/do now. i realise that its probably only good for the drain now but would love to know what went wrong so that I can correct before the next brew.
I have made a few great ales but I realise these give less issues than lagers.
Can anyone advise.
I made a Coopers European in Feb this year and this also stopped fermentation at the dreaded 1020. I just put this down to a kit and probably poor yeast but i would have thought that this AG beer would've fermented in no time.
Can anyone please advise. Would love any ideas.
Regards
Tim

Off the cuff, it sounds like too little yeast for your lager.  You did a different starter with each tube of 1 L each?  I probly would not have aerated post pitch. If you want to try to save it I would rehydrate some dry yeast again but also then add a starter gravity wort to that and/or use a fresh tube or pack pitched to a small starter.    Once the starter shows strong activity pitch it.  See what happens.  Sometimes what you think is a fail turns out pretty good.

Just two questions
Are you using a refractor or hydrometer to measure the FG.
What temp did you mash at.

Are you correcting your refractometer reading for the fact that the beer contains alcohol now? The presence of alcohol in the beer affects the refractive index such that your raw reading shows a higher reading than it would if it contained only sugar.

BeerSmith has a refractometer tool which will convert the readings for you. When I played with some numbers I got the following:
Your OG was 11.8 Brix, which equals 1.046
After fermentation, your reading was 6 Brix which in unfermented wort would be 1.022; BUT, in fermented beer with an OG of 1.046, 6 Brix tells you your adjusted gravity is 1.010!

It sounds like your fermentation worked as advertised. Unfortunately, aerating the beer will encourage oxidation. You may be able to blow CO2 through the beer in hopes of carrying off the newly-dissolved O2. I doubt the S-23 will have any bad effect; it should settle out since there's nothing there for it to ferment. Hopefully, others will have better suggestions.

Now you're probably asking yourself why the refractometer didn't come with a large red card explaining the need to compensate for the alcohol. Good question!

Hi all,

Thanks for the replies.

Im just using the refractometer with no conversions - thats the mistake....  Cant believe it.  Ive always used an hydrometer and thought the refractometer was just a straight forward replacement - no conversion etc.

The yeast starters were made in separate Erlenmeyer's and then both pitched into the beer.  They were made to 500ml then to 1000ml each, wort separated then pitched.

I multi stepped mashed in at 55C - 65C - 75C.

bravo durrettd, i've got my first refractometer in the mail and you've just saved me the learning process that timtoos has gone through.  thanks for taking one for the team, timtoos

Should I just tip this brew since Ive banged loads of O2 into it or is it worth purging with CO2 to try and knock the O2 out of it??

I think I might be wasting my time with this brew :-/