TDS measures the level of all total dissolved solids in the water. There is no direct relationship between that and KH. Which higher TDS COULD possibly mean higher KH, that's not always the case, as more TDS could mean more dissolved solids of another kind, and KH could be unaffected
TDS measurement can't replace knowing KH values in my opinion.
The Fraternity of Dirt
If at first you don't succeed,,, keep kicking it RubberSideDownOnTheLanding, 2-75g planted, 5-55g planted, 5-20g planted, 110g w/30g sump, 8-10g, Refugium, doghouse/newbie 2012 update adding table top pleco pans & a 90g (Nutz)