Topping off?

Ok the past few beers that I have kegged had such a large yeast cake that when it came down to kegging them I only had 3.5-4 gallons, my question is can I add water then to bring it up closer to 5 gallons? Or just let it go?

Personally I would rather have the beer at the final gravity it is at, even if it's a short batch, then to add water. There's a few risks involved, as well.

I had that issue a few times. Although never that low. You need to work on tilting the bucket when you siphon. Also, most kits are based on the topping off to the 5.25 gallons when putting in the fermenter. That should get you closer to 5 gallons in the end.

Also, you didn't say how long you left it in the primary. Generally if you leave it in for 3weeks+ the trub/yeast cake layer will become more compact and help you out also.

Brew a larger batch and ferment in 6 to 6.5 gallon carboys. You just need to determine how much extra to brew depending on your losses (brew kettle losses to trub, fermeter losses to trub, hydrometer samples, etc.). That way, you can ensure that you'll get 5 gallons into the keg. Typically, I account for about a 1/4 lost to the BK and 1/4 lost to the fermenter & hydrometer. I plan my batches to end at a post boil volume of 5.5 and plan to get 5.25 into the fermenter and 5 into the keg.

I had that problem, but fixed it by brewing 6 gallon batches. If you use fermcap, it cuts down or even eliminates loss via blowoff.

Put a piece of 2x4 under the front of the fermenter when you siphon out, it helps. When you get to the last bit, tilt it more and move the siphon around to get the last bit, without sucking up cake. With a little effort, you can get to the point where you are only leaving a few ounces behind.

+1, 6 gallon batches ftw! Why spend hours brewing only to fill a keg 3/4 of the way up? 6 Gallons allows you to leave junk behind in the kettle, and in the fermenter, and still get a solid 5 gallons.

I'd just let it go. Are you letting the beer sit in the fermenter for 3-4 weeks? Because a cake will compact 95% of the time. Many of my beers have a gallon+ of trub at the end of fermentation, but 3 weeks later, only 2-3 pints.

bonus to a slightly larger batch is, if you have more than the keg will hold, you just put it into bottles, and toss a carbtab into each of them.

1 to 1 1/2 gallons is a lot to lose how much is going into the fermentor? If you are getting 5 then at most you should lose is 1/2 gallon or less. Longer primary will compact the cake .I cold crash every beer I do by the third or fourth day the cake is so tightly compacted I can tilt the fermentor almost on its side and the cake don't move. I leave maybe a pint at most