2 aquaclear 10 filters ona 75 gl tank

[fish_bay]

are they any good? with 2 of these will be better to get a sump pump or external filters will do the job ??

 

[obscurereef]

It would be better to get a sump or canister than HOB filters. A DIY sump can cost less than a canister filter and there's tons of youtube videos on how to build one. Not too hard. For SW filtration, you want twice the max rating, so if had a 20 gallon tank, you'd want a filter rated for a 40 gallon tank.