pumps....general rules for sizes.

-Move the amount of the fish's water( in the tank) at least once per hour.
-Need to know the 'head' of the water being lifted.....

measured from the surface of the water in the (sump) ...in your drawing, the surface of the fish tank, to...how high your pumping in 'feet'.
-Your pipe will 'add' some restriction of flow, especially, once it builds up a bio-film inside of it.....
-this adds to the 'head'
-over size your pipe slightly in size....this will help both problems.

You take the total 'head' and the gallons of your tank, Then you start looking at the pumps 'curve performance chart' .

The 'gallons per hour', on the box/or ads most likely will be for.... NO HEAD HEIGHT.
The pump may be marked as moving 50 gals an hour, but when you try to pump "up" to... say 4 feet, it may just dribble out ...or not at all.

Here's a example ....look for the performance curve chart at this link (s)....
http://www.aquaticeco.com/images/static ... es/MD2.gif
http://www.aquaticeco.com/subcategories ... %20pumps/6

Aquatic eco has smaller pumps, they have the performance charts 'in the catalog', but not always 'online' (on some). Most often online, a pop-up window asks ,if you need help. Or, you can always call them.

With out the chart your buying 'blind'....even with a chart it's an informed guess. How 'cheap' is buying twice ?
Better to go 'bigger' (with in reason)....you can always divert, part of the flow to a 'spray bar' , to help add oxygen to the water.....or add more grow beds later on....

When I bought my first pump....I regretted not buying the next size bigger.... I was trying to save a few 'bucks'.


"When" you do a larger system....then you'll want to compare the wattage useage, on the pumps too.