How can i switch ac using semiconductors?

i was wondering if its possible to use my arduino to switch ac power? i would like to stay away from relays. im trying to avoid any moving internal parts. basically im looking to bypass my aquarium heater's internal thermometer, i have a ton of dead heaters that have broken internal thermometers. i want my... show more i was wondering if its possible to use my arduino to switch ac power? i would like to stay away from relays. im trying to avoid any moving internal parts. basically im looking to bypass my aquarium heater's internal thermometer, i have a ton of dead heaters that have broken internal thermometers. i want my arduino to sense the temp, and switch the heaters on and off.

thanks for any help...
Update: so i guess just by the sounds of that i would be using the 5v to run a led, using the led to switch an octocoupler and using the octocoupler to run the triac? is that because the triac needs a higher voltage than 5v to switch on? if thats the only reason wouldnt it just be easier to use a transistor to switch a... show more so i guess just by the sounds of that i would be using the 5v to run a led, using the led to switch an octocoupler and using the octocoupler to run the triac? is that because the triac needs a higher voltage than 5v to switch on? if thats the only reason wouldnt it just be easier to use a transistor to switch a higher voltage to run the triac?
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