Extra air in the jug..... ♪

It can live with headspace for a week, maybe two, but rather than bottle it early (its so much nicer to batch age), fill the empty space with fish safe glass beads from your local pet store. They won't hurt your mead and will fill up that nasty oxygen room. There's some other options too, such as getting a can of CO2 from your LHBS and blanketing the mead with it, or for short periods putting a layer of mineral oil across the top...I just don't have experience with the other methods. Do a quick search on headspace and you'll find lots of info though from people who do!

How clear is very clear? Mead usually takes many months to clear fully, oftn well over a year, unless you add fining agents.

You should be able to read fine print held on the opposite side of the carboy. Also, if you shine a flashlight through it, you shouldn't see the beam.

And yes, headspace is very bad. Try some searches for headspace in the title of the thread and it should dig up solutions for you, we've had a ton of threads about the subject.

The large airspace may potentially allow oxidation and/or spoilage organisms to destroy your mead. See This thread on topping off... .

The most important thing in making mead - stop worrying, this is not a hobby that benefits from worry! If it cleared faster it cleared faster, not a problem (I'm betting it will still get clearer though, when I first started out I thought some of mine were clear but I eventually learned they still had a ways to go!).

It'll be fine.

hi-jacking a bit, but weighing bulk aging...

I finally got my mead to ferment in a month (through the advice of many at this site) and have a month on a bulk age thus far. I luckily had a friend with CO2 so when I racked off the primary I blanketed the mead...I think.
I got the SG down from 1.100 to 1.002 before I racked, so it should be medium-dry to dry, but I would really like to try it to see if it mellowed out (quite strong alcohol taste when I racked) and I had planned on doing some back sweetening.
My problem is that I no longer have CO2 and there is quite a bit of headspace, so I have to decide to fill with marbles, back-fill with new must trying to get the sweetness right, or moving to smaller gallon containers.
Eventually I want to break it into gallons to oak two, try some spices on one, and have one traditional.

My question is how important is the bulk aging all 4.5 gallons of my mead vs. one gallons?
Also, as long as I blanketed the mead with CO2 and put an airlock on it, is the mead okay to continue aging with quite a bit of headspace, or will O2 slip in?
much thanks!

The trick is that "blanketing" is actually a myth, yes CO2 is heavier, but it will still disperse rather rapidly, it never forms a neat and tidy layer at all.

That said, purging with CO2 works very well. So if you pumped CO2 into it for a little while (I honestly have no idea how long, I imagine it wouldn't take long at all in a carboy to get the majority of the O2 out) and have since left the airlock on it should be ok. There's always the possibility of some leaking, but that's hard to judge whether it's happening and to what degree with a stopper, so it's a bit of a guess (to me anyways).