Fermenter Volume

Hi guy's, may I ask do you guy's top up your fermenter volume after boiling , cooling and drainage to bring  losses back to bottle volume, and do you check original gravity after top up or before top up. ( I brew all grain)
I've been topping up to restore losses but I'm beginning to think it may be better to take the loss as I'm thinking topping up may be lowering the OG reading and taking a gravity reading before top  up would possibly be a false reading. 

Check out the "Dilution Tool" under the tools tab in BS2. It does exactly the thing you're asking. You just need to know the volume you have in the fermenter, and its specific gravity. Punch in those two numbers and the volume of water you plan to top up with. It'll tell you your final volume (i.e. 5 gallons) and its diluted SG.

I top off when making wine so as to keep head space at a minimum, but I've never topped off a batch of beer.

Hey there Rooseterbrews. I also do all grain in fact Brew in a Bag... Am in Sydney Australia and also had this issue...I have found that its best to put more water in at boiling time, so that you can come out with a bigger batch... this way you wont have to risk any infections from non boiled water.

And yes your OG needs to be measured after you have added any water to your fermenter, if you do that, because any more clean water will dilute your wort.
We are metric so 5 gallons is 19 Litres, so if I get 18 litres or even less I never add water.

Quality is better than quantity.
my OG's are normally around 1050 and if using a Saison yeast which will get down to 1000 its a pretty strong beer already.

I have just made a chocolate Stout using baking chocolate and managed to start at 1060 by using 1 kg (2.2 pounds) of extra grain.

I have 20 Litres in fermenter, but lots of trub because of the chocolate so I am happy if I bottle even just 17 or 18 Litres of that.

George

I never top up anything after the boil. The time to adjust is at kettle top up before boiling.  The pre boil SG is checked, top up to the required level if SG allows,  and then careful monitoring of the boil to ensure you boil off the right amount is key. If volume is low at preboil and SG is right, I suffer the loss and don't dilute. If I have high SG at preboil, then top up only to estimated preboil volume level. If you have low SG and too much volume you can boil longer.

I have topped off at the beginning of fermenting. If you put your fermentation volume in BS then the gravities are calculated on that volume. So if you end up with 5 gal after the boil in the fermenter and you programed for 5.5 gal then adding .5 gallon should make it all right. I rarely have to add anymore, because it usually works out as planned. Actually if you look at the "brew steps" in BS it will tell you to "add water if needed to achieve final volume of 5.5 gal (based on my setup).