Batch sparging advise

[Fal]

I'm trying to understand Batch sparging. Is this correct:

if I plan on adding 30l of water to mash I do two steps:

1. Add 15l to grain at 68degrees (or temp appropriate to recipe) and steep for 40 mins

2. Drain mash tun then add second 15l at 73 degrees (Or again temp appropriate to recipe) steep for 20 mins and again drain mash tun.

[Mudder]

You have the general idea down, but there is devil in the detail. You should added enough water to the grain so that you have a water  to grain (grist) ratio of somewhere between 2.1 to 6.3 l/Kg. I generally mash in at 2.6 l/kg so I would add 2.6 litres of water to every kg of grain in the recipe. You want you water and grain mix (grist) to be around 68°C when combined so the water (strike water) should be a higher temperture to start with. There are many calculators on-line which will work out this temperature difference for you such as this https://www.brewersfriend.com/mash/.

You can mash the grains from anywhere from 40 to 90 mins but generally around 60 minutes will do, then drain the mash tun. You need to add the remaining water left from the initial 30l at this stage, this is generally added at a higher temperature as well so the the mash reaches it mashout temp of 77°C (which helps loosen the sugars), again the calculator will tell you this temperature. You should mix the mash with this water and allow the grain bed to settle, 20 minutes is pretty long for this as all the starch should be converted during the initial mash and this second additionof water is only used to wash the sugars out of the grain. Also if you want 30l in your boil kettle you need to take into account the volume of water that is adsorbed by the grain during mashing which will be around 1.1 l/Kg.   

[LordEoin]

yeah, i always round it off to a liter per kilo, so if i have 5kg grain and want 30l in the boiler I'll use 35liters of water.

remember to recirculate a few liters too before draining the mash tun. Just let it run slowly into a jug and pour it gently back into the mashtun without upsetting the grain bed.
This will ensure that any loose bits of grain are cleared and the grain bed will act as a filter for the rest

[Fal]

Ah right, I get it now. Some of those calculations on beersmith are beginning to make more sense!