An acidic rinse is designed to lower the ph if you use a high ph alkali. Rinsing standard MS with an acidic in my opinion will lower the ph of your 'water rinse' and may reduce it's effect, but as Richie says some do use it. I use a standard MS and rinse using a 50% dilution of prochem's pureclean or chemspec's dfc 105 as a booster in warm water which I believe breaks the surface tension of the water and it works very well on those more challenging carpets. Agitation is an important part of the process particularly with splitters and I always leave a 10 min dwell. You may find you want to put something in the solution tank because it just feels right
. Otherwise I prefer warm water as I find cold water less effective which is just a personal choice. I suggest trying it to see which you prefer, Solutions, Amtech, Prochem & Cleansmart all supply their own brands splitters. Sometimes though Powerburst or similar is the only way to go and that's when an acidic rinse is at it's most effective to remove detergent residues to prevent re-soiling and lower the ph. I use Clearwater Rinse from Hydramaster excellent product and cheap as chips.
Simon