This is very helpful. I usually squeeze the bag to avoid acidifying my RO water, and this has been fine.. I've done it in the past and it increase my efficiency a couple of points but I was worried about tannins so I stopped the practice. I think I'll give it another shot. Thank you....so what about tannins? If im pouring 168 degree, straight RO water over my grains for BIAB, aren't tannins going to be released if RO pH isn't low enough?
Nope. With almost no alkalinity, the pH of RO is like a feather in the wind. With any external acid, its pH drops like a rock.
Another important fact is that RO water almost never has a pH about 7. In most cases, the pH of RO water is under 6. Part of the reason can be due to dissolved CO2 in the raw water that easily makes through the RO membrane into the product water. That dissolved CO2 along with the very low alkalinity means that carbonic acid is formed, which quickly depresses the water pH. I had an unfortunate client that called me in too late who had this problem with their brewing water and the resulting beers came out very acidic. With nearly 300 bbls of acidic beer that they ultimately had to waste, the economic impact was the end for that brewery.