Looking for in-line heaters

[Shnot]

i have recently set up a 90 freshwater tank and want in inline heater to go with my canister filter but am having a problem with my output tube being 3/4 of an inch / 19mm all the inline heaters I've seen only go up to 1/2in /12.7mm any advice on how to make this work with adapters or maybe a heater made for larger tubes any help would be much appreciated