Yes you should calibrate but 1.025 is just about perfect. I guess you could tweak to 1:026 but I sure wouldn't freak about 1.024. But yes calibrate. Remember if the critters are upset it will show, via your eyeballs. If you test something and it doesn't seem right, retest, then do it again, then do it with another kit. A healthy looking tank might benefit from a tweak but rarely is it necessary to make a radical change to a tank that looks right. Now if the tank looks like poop (and yours does not) then you need to react but in your case just tweak the edges.