[Myka]

Testing can be frustrating because the kit is only as accurate as the user. Be very careful when measuring water, measuring powders, and make sure the drops are even. Do it the same way every time. Use a knife back to level off the powders, hold bottles "perfectly" vertical (not on 45 degrees), and get air bubble out of the syringe when measuring water. Sometimes the first drop out of a bottle isn't a "perfect" drop and shouldn't be used. If you just fill to a line on the test tube, get a syringe and measure water instead. Test, dose, wait an hour, test again. This way you know how much a certain amount of dosing affects the tank. Knowing this can also help when adjusting dosers as you should be able to figure out mL per minute and how much is dosed per mL. Finally, test at the same time everyday...preferably in the morning before the lights come on. Testing in the evening after lights go out is a good time too. Also, when I adjust dosers I only adjust by a couple minutes at a time. If I adjust a doser I always test that parameter as the end of the dosing cycle (I dose calcium during the day and alkalinity at night).

Provided the testing is accurate...

What salt mix are you using?

Alkalinity can be a giant PITA to keep steady. I would say get the Mg down to normal levels, and then forget about it for now. Concentrate on one parameter at once because adjusting one will impact another, this is why you're seeing really wacky numbers. Once Mg is in a relatively good place (say somewhere between 1250-1400 ppm), concentrate on calcium (somewhere between 380-440 ppm), then look at alkalinity (6-10 will be fine for now).