Sorry to not understand - but do you think you could explain the problem again? Are you suggesting that, instead of adding chemical to make the new water habitable for the fish he just check to see if standard water would be okay? Or are you suggesting testing the pond water to ensure that there is nothing in it that would make it dirty faster?

If it's the latter, then you might have a point, but I think you generally just have to accept that 'living' ponds get dirty and require a clean out every now and then to look their best.

Does this help? If it doesn't I'll be more than happy to assist one you've clarified what you want