PS234 & HTH 5-way difference...

I've tested with my two test kits, P234 & 5-Way HTH. The HTH test kit is from Walmart and is brand new. All the numbers match except for the alkalinity. Why am I getting two different alkalinity results with each test kit? Shouldn't the results be the same? HTH was 240 yesterday and 210 today. PS234 was 190 yesterday and 160 today. Comparatively, the numbers went down the same ppm from yesterday. (I've been adding muriatic & aerating) However, my concern would be for those out there who are using the 5-way while awaiting their kits and adding acid to their pools that might not be necessary. My inclination is to go with Ben's kit numbers. Any input? :rolleyes: