Mustang wine too acidic?

So I'm trying my hand at mustang wine this year. The wine has been fermenting for 9 days and is only down to 1.010 from an OG of 1.090 using 71b. I have not measured my pH yet, but I know mustang wine is very acidic. When I tasted a couple of drops after the last hydrometer reading last night it tasted slightly sweet but very acidic. I have some chalk (can't remember what the real name is for it) to lower acidity, but I thought I was supposed to use this after fermentation to balance taste.

Is there another method of acid reduction other than dilution that can be employed during fermentation? Thanks guys!