It is not only that but the Maven test water will have to be discarded and replaced. The iV test you can put the water used to test back in the tank unless it is a small tank.
That is not a response that makes any sense or can be taken seriously at any level.
1 - They are the same pH based test, one just has a visual pH indicator added.
The insanely low concentration of indicator dye is likely harmless even long term if the test water were returned to the tank, just as with probe based test.
So let's get to your argument:
Even if the Maven dumps the test water, so what?
$100 for 200 gallons of saltwater is $0.50 per gallon.
Let’s say a complete test cycle somehow wastes an insane 500 mL per day. Lets round that up to 1 gallon per week.
If you do water changes, that water is not “wasted.” It is simply part of the water change you were already going to do. On a 20-gallon tank changing 20% per month, you would just change roughly 3.5 gallons instead of 4 because the tester already removed the other half gallon. So even on a tiny tank, it is irrelevant.
No water changes? Let's talk real-world numbers, maybe 200 mL or so of water per week, testing several times per day. Let's round it up to 500 mL just for fun. That is maybe 10 cents per week of water if you run multiple tests per day, a fraction of the reagent cost. But what about the amortized cost of the tester and the non-reagent consumables, such as tubing replacements?
Let's call the Maven $1,500 in the door, tax, shipping and all. Let's amortize its cost over 3 years of testing. Five parameters 3 times per day is 15 tests per day. Over 3 years, that is about 10 cents per test in hardware cost. One series of tests per day, that goes to about 30 cents per test, and you want to dither about the cost of saltwater being returned vs. wasted? It's not a serious point.