If the canadian channels are clearer (just snow) , no ghost, then a good low noise pre-amp is perfect for you. CM 7777 being the highest gain version at the same price tag of its brother the 7778. 165 km is far far away but still closer than the 90 nautical miles from havana to the southern most point in the lower Florida keys (over 200 km to Miami) yet analog TV signals from Miami and Ft Myers were received reliably everyday ( with sudden few seconds fading some days) with a 3 stage home made low noise pre-amp. Granted power levels from Ottawa stations are quite low compared to the american florida based signals but in any case you are getting something that can be improved (snowy analog, no ghost).

Trees in the path play a major factor and with any digital link , even trees close to the path in extreme hot weather also radiate a lot of thermal noise that could play a role, but you either cut them or increase the hight of the tower, no other solution there.

That antenna is rated for VHF , 100 miles, and UHF , 65 miles , and most channels will be in UHF in most markets, therefore you need a pre-amp since your target stations are above that.

Another important factor is the current power levels for those digital stations, they might be low now as it is the case in Toronto , but they will increase to normal levels in 2 months , therefore maybe waiting for the sea to settle after the storm would be a better idea althought a good pre-amp will always help in your case.

Newer TV should (although not necessarilly a true statement) have newer ATSC tuner with better capabilities when dealing with weak and problematic signals. It is not the TV tuner , it is the 165 km and low transmitter power combinations. Maybe you can find more info in regards of future final power levels for Ottawa.