Inline heater restrict flow?

[Nehemiah]

Hey everyone, I have a gretch canister filter that has 1" hoses on it, and I need a heater. I was thinking of getting an inline heater, but the one I'm looking at has 5/8" connections. Will I see a considerable drop in flow if I splice in the heater? It's on a 100 gallon stock tank, filter is rated for 200 gallons. The heater I'm looking at is a hydor 300w inline.

[Fishnut2]

I'd heat the water at the stock tank. I'm not exactly sure how the inline works, but if flow stops for any reason...wouldn't the inline heater burn out? Does it have a thermostat? I'd use a 300W submersible on the stock tank, and cover it (stock tank) to help it stay warm, and keep humidity down.