Not to sure on how much to spend, whats the differances between a maxijet and a korilia? How many should I have? I'm thinking I want to make it a reef tank, not 100% sure yet.
Powerheads fall into two main categories. First, you have centrifugal design. These work like a standard pump, with an impeller in a circular housing. These work well, and are dirt cheap. Funnily enough, there is not much cost variance between crap powerheads and good powerheads of this design. In this category, I would wager that the vast majority of users would agree that Maxi-Jet is the best out there.
The pros of this design are:
- Cost
- It's an old technology so units are generally very reliable
- They have moderate pressure capabilities so you can drive little stuff like UV units, HOB fuges, etc with them.
Cons
- They create a very high velocity stream of water that can rip corals apart that are placed too close.
- The flow rate is pretty low... few hundred GPH usually.
Second, you have the propeller style. These work like a ship's propeller to move water. They have a much larger opening and move incredibly huge amounts of water.
Pros
Very high water volume... can be over 1000gph
Flow spread over a large output orfice, allowing much more distributed flow
Cons
Cost
New technology... units are expensive and sometimes buggy.
The Koralia is the one exception to this. These units are inexpensive prop style units... about 40-60 bucks each. They work well, but older units had a reputation for electrical problems. They have a nice magnetic mount that works very well. I have purchased four of these for my new tank project, looking forward to using them.
Hope this helps clarify it.