Hydor in-line heater

[sweetness8t5]

Would it work for a HOB filter?
And what size/power/etc do I need for a 55g?

 

[rich311k]

They need to be in a hose. I guess you could do it with a closed loop and a powerhead. They will not work with an hob. A good rule of thumb is 5 watts per gallon.

 

[Lonewolfblue]

Would it work for a HOB filter?
And what size/power/etc do I need for a 55g?

Nope, won't work with a HOB. They have a 5/8" input and output connection, and are made to be inline with the canister tubing.
The ETH 200 is 1/2", and the ETH 201 and ETH 300 are 5/8".

 

[sweetness8t5]

I was going to buy a second filter anyways... guess this way, my choice of filter is easier