89 degrees with no heater? That is really high....at what temp do you keep your room temperature? Even in summer when my house temperature creeps into the 80's, my tank temp is usually several degrees cooler.
If you house temp is at 75 degrees, that would mean your pumps are heating up the water 14 degrees. That's high even for a submersible pump, much less an external inline. Addiontionally, you have 450 gallons of water plus what's in the sump. That's a huge volume.
89 degrees should feel very warm if you stick your hand in the tank. If you have been keeping aquariums for a while, 89 degrees should be shockingly warm to the touch. Can you test the temp with another thermometer to ensure that your controller isn't giving a false reading?
If you house temp is at 75 degrees, that would mean your pumps are heating up the water 14 degrees. That's high even for a submersible pump, much less an external inline. Addiontionally, you have 450 gallons of water plus what's in the sump. That's a huge volume.
89 degrees should feel very warm if you stick your hand in the tank. If you have been keeping aquariums for a while, 89 degrees should be shockingly warm to the touch. Can you test the temp with another thermometer to ensure that your controller isn't giving a false reading?