I'm unsure what 'parasites' you're referring to, but all obligate parasites die if they don't have a host within their normal life cycle. So, if you know the life cycle of the parasite and it is shorter than the time your tank has been fishless, then the parasite has died.
In the case of Marine Ich (
Cryptocaryon irritans) eggs aren't laid anywhere. 8 weeks letting the tank go fishless WITHOUT having added anything that might have brought in contaminated water is enough to kill off all commonly known variations of this parasite.
MI is not temperature sensitive in the ranges we need to keep our marine specimens. The concept of temperature to 'get rid' of MI or shorten its lifecyle is not supported by what we know about MI. The mis-information/rumor comes from the knowledge and work done with the freshwater Ich:
Ichthyophthirius multifilis. In fact, that is how Marine Ich got called "Ich." It was misnomer carried over from the
Ichthyophthirius sp..
Freshwater Ich is sensitive to heat. In fact it can be almost irradiated by heat alone, providing the fish can handle the heat. It is the Freshwater Ich that will reproduce at a rapid rate when the heat goes up. Marine Ich might reduce its cycle time with heat, but it isn't always a guarantee. In the case of the lethal temperature for MI, so much heat is required to stress the MI that the fish would die before the MI would die. MI has a wide survival range going down to below 50F!
I keep my tank at 75-76F. It is a FOWLR setup.
Dr. Burgess has found that the short termed cyst stage of the MI cycle can actually extend out from the average 4 to 10 days to more than 6 weeks! Heat doesn't necessarily increase or decrease this stage. This is what has led to the 8-week safety net recommendation for a tank that has MI to go fishless. You'll note this 8-week recommendation is not connected or related to any temperature requirment. Time not temperature is the killer.
You're doing it right, if you haven't been adding things to your aquarium that may have brought in contaminated water or contaminated organisms. Congrats!
