Zorden,
it takes hours, perhaps days for skimmate to dry up and thicken.
you are right to say that the new skimmate will mix with the old ones. as i've mentioned before, only minimal will retreat back into the tank. most of the "scum" will remain at the top layer of the foaming. unless the collection cup is filled up and left to run for months, there shouldn't be significant effect on the tank parameters.
I cannot calculate the amount of concentration of old skimmate and new skimmate, but from our understanding, it shouldn't differ much.
I cannot confirm the exact amount of skimmate that will retard back into the tank. But I CAN assure that the tank condition will not be any worse than if the skimmer is not skimming.
We have already concluded that our beckett skimmers can be used in-conjunction with a auto-shut-off waste collector. I believe most who had shown interest in this thread do. When used together with a waste collector, the skimmer WILL NOT overflow.
If the skimmer is left running (but not skimming) for weeks without anyone attending to it, the tank parameter will DEFINITELY worsen.
Same thing applies for our skimmers, whereby our collectio cup is not air tight, tank condition will also worsen if left unattended for weeks.
End of the day, even if one has the most expensive, sophisticated equipments, a reef tank might not survive if the owner practises ill-husbandry. It is good husbandry that decides the success / survivability of a good reef tank.
We strongly advise that skimmers should be cleaned at least once a week.
Regards
Ocean Werx