Question about sparging?

[RRising]

I have a question about sparging... I think i am batch sparging but do i go until the gravity reaches around 1.010 or to the OG of the particular recipe?

This has been confusing me and i cannot find a straight answer.

 

[MHB]

I think we need to be sure which type of sparging you are doing.
Batch sparging, you drain the first wort, then add a second batch of hot water (hopefully acidified), wait for a while and then drain all the second wort into the kettle.
Sparging (I hate "Fly Sparging" - bit like ATM Machine), you drain most of the first wort so that only 10-20mm is left over the grain bed, then start adding hot water (ditto) at the same rate as you are draining.
This is when you have to choose when to stop.

If you are batch sparging all the second running will be the same gravity, so no point/cant stop at a given (i.e. 1.010) gravity but may choose to stop at a chosen volume.
Either way it is really a matter of water management, with a bit of calculation and experience you should have a very good idea of how much water you will need to hit both your volume and gravity.
Mark

 

[RRising]

I think we need to be sure which type of sparging you are doing.
Batch sparging, you drain the first wort, then add a second batch of hot water (hopefully acidified), wait for a while and then drain all the second wort into the kettle.
Sparging (I hate "Fly Sparging" - bit like ATM Machine), you drain most of the first wort so that only 10-20mm is left over the grain bed, then start adding hot water (ditto) at the same rate as you are draining.
This is when you have to choose when to stop.

If you are batch sparging all the second running will be the same gravity, so no point/cant stop at a given (i.e. 1.010) gravity but may choose to stop at a chosen volume.
Either way it is really a matter of water management, with a bit of calculation and experience you should have a very good idea of how much water you will need to hit both your volume and gravity.
Mark

I was batch sparging, like in the Keg King robobrew tutorial video.

How do you calculate how much sparge water needed?

 

[MHB]

You work backwards from some point, be it volume to package, to fermenter, at end of boil or kettle full.
No hard and fast rule on where you work from, but say you wanted 23L at the end of the boil.
You need to know how much water you will boil off, usually around 10% so your start of boil volume would be, well V=23/0.9 or 25.6L
If your grain bill was 4.8kg and we assume about 0.9L/kg absorbed by the malt we need to add 4.8*0.9 = 4.23L
Out total water requirement is 25.6+4.23 = 29.8L (call it 30L) as there will always be some other losses (in tubes/jugs, sample jars evaporation during the mash (~2% is the standard number)), comes to about 0.6L and a bit for rounding, I would be starting with about 31L. A bit of experience on your system and keeping good records will let you dial all the numbers in pretty tight.
With a Robo (or Grainfarther, Braumeister...) I would do what they recommend (at first) but there are plenty of other systems.
You really cant mash in any heavier than around 2 Water to 1 Malt (the malt wouldn't all get wet if you did), using about half your water for mashing in is pretty common if you want to make some hot water additions for temperature steps.
The total water available/needed is 31L to 4.8kg of malt or a Liquor (water) to Grist ratio of 6.46:1. You could use all of it and do a no sparge.
If you mashed in with half your water 15.5L, you would have the same left for sparging.
At a minimum you would want around twice the grain weight to do an efficient sparge so 9.6L (call it 10L) giving you 21L to mash in with or (mashing in at a L:G of 4.375)...
Lots of options, and depending on what your doing they can all be right!
Mark

PS
Sparging only works efficiently if you do it slowly, with hot (75-80oC water) and pay attention to the water chemistry (to prevent leaching tannins) a modern commercial 'High Speed" lauter would take 90-120minutes and that's with a grain bed 150-250mm deep (very fine grist compared to what most home brewers use) but they get efficiencies in the high 90%s (95-98% being common). If you want to get your head around sparging I would recommend the appendix in How to Brew by John Palmer He covers the flow dynamics pretty well, anyone designing a lauter tun would find it very useful.
M