Batch Sparge Question

[Blancaster]

Ok, So I get the first part. Figure grain temp, plug into beersmith, and get your needed water temp.
Example 72F grain, need to have a mash temp of 154, so mash in with 163.6 degree water, and you should come out about right.
The 2nd part Im not getting. So after I vorlauf and drain, I need to sparge with 160F water.
Here is the part I don't get, do I really just use 168 water? Because once I add to the now cooling grain, the temp will drop down quite a bit in the tun. Or do I need to jump that temp up to like 178 or something to achieve a final temp of 168 for my sparge?

[SkyBrew]

Jump the temp up to 178-180

[msjulian]

I fly spare with 175 - 180 degree water (as Sky mentioned). I would suggest heating your batch spare water to 178 +/-. Vorlauf as normal after the mash. Drain and then pour the sparge water in and give it a stir. Let is sit for a few and then vorlauf and drain.

[Blancaster]

Thanks for the info!
One other question. If I use 5 gal of RO water and the rest filtered tap water. Do I need to ratio it between the initial mash water and the sparge water?
How does everyone else do this?
With BIAB I just put it all in at once.

[msjulian]

I use the same blend ratio on the spare as I do on the mash. Some reading says this is not totally necessary but I it is just what I have always done.

I did do an interesting experiment today concerning sparge water and mash ph. I am writing a tech article for homebrewtalk.com and performed part 1 of a two part experiment today and as soon as I finish part 2 I will get it up on their site and link to it.

[Don]

It's recommended to use the same water profile as your brew water or use RO.
You should also have your sparge water lower than pH 5.8, 5.5 is best.
(Phosphoric Acid works great for lowering your sparge pH, if needed).
PH has a greater effect on tannin extraction than temperature.

Sparing involves gently rising the mash with hot water to dissolve the converted malt sugars so it can run out easier.
Spare water should be 168 to 170 degs (adjusted for loss from the your hot liquor tank).
Lower temperatures aren't as efficient in dissolving sugars and don't fully denature the enzymes.
Higher temps can extract unwanted flavors, if the pH is also too high, and can cause unwanted starches (ones with no enzymes to convert) this will slow down or stop up your lathering.

I used to use a pie pan with several holes punched in it, and let that sit on top of the grain bed to spread out the spare water.