The 5 stage RO filter has two extra activated carbon filters to improve the filtration over the 3 Stage version.
As we all know, water supplies vary a great deal from region to region. Brewing stout in a hard water area is okay because of its high Calcium and Magnesium content but not suitable for the lighter beers such as Lager and IPA.
Your tap water is going to contain other chemicals which are added by the water utility companies, such as chlorine or chloramine.
There is a way to provide you with a “blank canvas”;
Reverse osmosis systems offer a cheap and effective way of providing you pure water.
The water is pressed through a semipermeable membrane the pores of which are so fine that only water molecules permeate, dissolved minerals and pollutants being removed with the remaining water which is sent to the drain. Once you have your base water you can add back the desired compounds to suit your brewing session. You can go to town and find out the water profile for a specific beer or keep it simple and add Calcium Chloride, Calcium Sulphate and Acidulated Malt in specific proportions depending on what style you are brewing.
Don’t forget to add Yeast Nutrients five minutes before the end of the boil.
Here is what AJ deLange has to say on the subject;
Baseline: Add 1 tsp of calcium chloride dihydrate to each 5 gallons of water treated.
Add 2% Acidulated Malt to the grist.
Deviate from the baseline as follows:
For soft water beers (i.e Pils, Helles). Use half the baseline amount of calcium chloride and increase the Acidulated Malt 3%
For beers that use roast malt (Stout, porter): Skip the Acidulated Malt
For British beers: Add 1 tsp gypsum as well as 1 tsp calcium chloride
For very minerally beers (Export, Burton ale): Double the calcium chloride and the gypsum.
There are replacement filters and membrane available to keep the unit in peak operating conditions.
Change RO Membrane every 9,000 litres or annually
Change PP Filter every 25,000 litres or annually
Change CTO Filter every 25,000 litres or annually
Change UDF Filter every 25,000 litres or annually
Water input = Red connector
Water output = Blue connector
Bypass water output = Black connector (this water contains the “bad stuff” and needs to go down the drain)