so I have been using the hannah checker for alk for i dont know, maybe 7 months. And have went through a few bottles of reagent. On fish of hex, he says when you are almost out of one bottle of reagent to test your alk, then right away test your alk again with the new bottle. So i did this today and my alk with the old reagent was 8.5. Exactly what I keep my tank at. Then I used a new bottle at it wad 7.7. What? Ok so I opened another new bottle I had and it was 7.4. So I'm really confused. I go grab my red sea alk test kit, and it reads 7. Have I been wrong all this time? Sure seems so. But I dont want to just react and dump alk in my tank. This got me thinking, is there a way I could make a solution to test my checker reagent. Likr if I mix x amount of brs sodium bicarbonate into y amount of water and it will give me a fixed dkh?