Which is better?

75g tank:

2 Marineland 350 Biowheel HOB Filters or Mega Flow model 2 sump filtration system or both?

 

as a general statement: sump>HoB filter. However I dont quite understand your choices.

I'm not sure what you would get out of 2 HoB filters? Is the plan to run different medias, or make one a fuge or something? If your just thinking of filtering more gph then its not really worth it.

While the mega flow is nice, check the price? Plus you would still need a return pump & stuff like that. a sump with live rock holds more benefits over bioballs too.

If you have room for a sump, your best bang for the buck is going to be picking up a tank and building your own sump. Then you can space you own compartments for skimmer, fuge, etc.

 

I am buying a tank from someone. Its a 75g tank and it comes with the sump. My question was if the sump would be better than the HOB that I already have.

 

500x better, HOBs are more so for freshwater or smaller salt tanks i would say.....theres plenty of benefits like added water volume so you have more of a buffer for a mess up, you can hide all your gear in it(heater, skimmer, etc) to have a lot more room in your main tank plus you could add stuff into a sump to make it more of a biological filter

 

Having / getting the stuff clarifies a little. I thought you were asking from the going to the store and picking one or the other up.

If it comes with one & you already have the other then use both. There is no such thing really as too much filtration.