Online Fluval states it will do 700 g/h. which is probably more theoretical but it is almost 10x the turnover of your tank. So actual at full settings is probably closer to 8? with filter media in it. Even if it was less than that you're over the recommended 4x turnover per hour that is recommended. So this filter will work wonderfully for your tank.

 

Currently using a FX4 on my standard 75g heavily planted tank with good results (about 1.2 years)

 

I've found a stat for the "filtering capacity vs pump capacity" for the FX6, but not the FX4. The FX6 claims 928 gph pump output but says it's able to filter 563 gph. That makes the filtering capacity 61% of the max pumping volume. If the same rate holds true for the FX4 that means it would only put out about 427 gph with clean media. That should still be more than enough for your tank it's about a 5.6X turnover. Youl'll just need to get the flow to the right places. I have an FX6 on my 125g and I've always been happy with it. With an FX4 on 72 gallons you'll have more filter flow per gallon than I have. Looks like you're getting a beautiful tank. Congrats, and keep us posted with lots of pics!

 

It kind of depends on your stocking

 

Should be perfect. Generally you want 4 to 8 times turnover for a planted tank. Much more then that and your plants will take a bit of a beating. Much less and you end up with deadspots. General rule is you take the advertised gallons per hour of any canister filter and divide by half to get real life numbers. You should be happy with the fx4.

 

Fx4 seems right for that size but I would personally get to the fx6 if you could. Sorry if this breaks some sort of rule but this video may sway you one way or another -

 

Yes, the FX4 will provide ample flow. But I recommend you a better option. Get a cheaper canister filter and buy a powerful inline pump. Hook up the pump to the outlet and never use the built in water pump, just use the canister to hold the media and let the inline pump move the water. I wish someone gave me this idea two years ago.

 

Yes, the FX4 will provide ample flow. But I recommend you a better option. Get a cheaper canister filter and buy a powerful inline pump. Hook up the pump to the outlet and never use the built in water pump, just use the canister and let the inline pump move the water. I wish someone gave me this idea two years ago.

Why? Whats the advantage of this over the FX4?

 

I run an FX6 and then just have a separate pump like you're describing with a separate intake for the reactor and the heater. I guess if you're using a different canister it might not be an issue, but one of the things I like about my FX6 is it shuts off the pump and burps itself twice a day. Other than that it's real quite and I never have an issue with gas buildup in it.

 

So, what did you pick?