It measures your Alk, Ca and Mg.
If you have the Dos you could have it make corrections but I personally would just use it to measure and then separately I would control my dosing. Too much room for error.
you would be much better off with the reefbot. i picked one up and cpukd not be happier. trident forces you to do min 3 tests a day and $45 per regent. insane. if you want to come by and look at the reefbot give a holla