Lowering PH Please Help

[fisherman]

hi lads,
Lets say I have lowered the alkalinity of my brewing liquor from 103 to 25 with CRS. I have fed my water analysis details into the water treatment calculator on this website weighed out the mineral additions and divided them by 50 ( brewlengh in litres ) then multiplied by 23 ( volume for mash ) for mashtun additions and added to the grist. When I dough in the PH of the mash is 5.8.
How do I lower the PH of the mash?. What do I add and how much time have I got to lower it?
many thanks for any replies

 

[fisherman]

By the way this is just a standard bitter.
8 kg M/Otter
600 grms Crystal
500grms Torrified Wheat
Cheers

 

[pittsy]

The trouble with crs is although it lowers your alkalinity it may rise your sulphate too high , i use lactic acid , much better imo . you could also try acid malt , for every 1% of acid malt as your grain bill your ph will lower by 0.1 . so you could either use both crs and acid malt or change to lactic acid and acid malt (if needed) Besides my info suggests your alkalinity for an amber balanced beer would be around 30 ppm