Hello; Not sure what the roof ventilators are actually called, but I have two on my roof. They are passive and even when working do not prevent some serious heat buildup in an attic space.
Last year I tried a homemade ventilation setup. I have a panel in the ceiling of a hallway which is the access to the attic. I first made a screen frame that fit the opening and placed aluminum screening in the frame. It is one of the metal frame kits that you cut to fit from Wal-Mart or other home improvement store.
My thinking being that the screeing in the opening to the attic would vent the heat from the house with the house windows open. It worked to a degree, but was not a big improvement. This warm season I added a 20 inch box fan on top of the screening. I have a switched outlet in the attic and can turn it off and on from the hallway. Having the fan on medium speed does pull a decent amount of hot air from the house. I can tell a difference but it is still warm in the house when we got some 95+ F days. Note that I do have central air but prefer not to use it most days. I do turn it on some evenings when it is real muggy hot. This does not keep the house from being warm but does keep it cooler than without the fan running.
As i have dealt with warm tanks in the summer for some time, the simplest thing I do is try to keep species that tolerate the occasional warm temps. This rules out some native species that do not do well in warm water.
I also run a good amount of bubblers in my tanks. In this house i have the airpump in the basement where it is both cooler and I do not have to hear it run.
I have also floated ice in tanks on really hot days.
Good luck