Except some of the other devices that just do alkalinity can put their waste product right back into the tank :-)The trident only removes about 50-70ml a day under normal operation (4 alk tests, 2 Ca, 2 Mg) - basically like a skimmer. There is nothing that puts more saltwater back into the tank. Most other devices that only do alkalinity use between 60-150ml per test cycle.
That's 0 loss, tiny gain from the reagent added during the test.
