Help with hydrometer

I'm on my 3rd brew (Belgian Dubbel) and I just added it to the primary fermentor. I decided to use the hydrometer this time and I want to make sure I'm reading it correctly.

After I added the wort to the fermentor, I took a sample, place it into the tube that comes with the hydrometer and slipped the hydrometer in. I got three readings:

Balling = 10
Potential Alcohol % = 5.5
Specific Gravity = 1.40

I know that I need to use the hydrometer to decide when to go to secondary. So, the SG readings should be higher than 1.40? When they are constant, I move to secondary correct? Do I need to take readings from the secondary to know when to bottle?

Also, do you see any issue with using dental floss to dip the hydrometer into the primary? The one potential issue I see is the yeast cake getting in the way. I guess I thought I could create a little hole. Or, maybe the yeast cake will be gone when I take the reading. It just seems easier than taking a sample and less exposure to the air.

One more thing, how accurate is the potential alcohol reading.

As always, thanks for the help.

Ersin

Ok both your reading, the balling and potential abv are ok. Your SG reading is actually 1.040. If you look farther down the hydrometer, 1.4 is not on the scale.
Since your SG is 1.040 your FG should be less then that, meaning 1.005. that just an example . you dont need to take reading to know when to bottle but when your reading stop changing, then go to secondary.
you can use dental floss, I do, just glue it to the top real good.
Potential alcohol is only good if you have absolutely no unfermentables. Also it will only work if your FG is always 1.000

Thanks for the tip. And, I'm glad the dental floss idea is a good one.

potential alcohol can be used even if you have unfermentables, and even if you don't get to 1.000. Just take your initial reading, 1.040. Write down the potential alcohol (5.5%). When the beer is done you will have a gravity like 1.005 or something. Write down the potential alcohol there (maybe .5 percent). Your alcohol content is then 5.5 - .5 or 5 %. make sense?