hey skiz mate how are ya?
i was meant to answer ya last pump question....
heres my 2 bob worth....i run a E+F set up with a 35l res off a 550Lp/h run from 13mm to 19mm, with 50L litres of clayballs in my 50L table, this holds 16L of water and fills it to a depth of 75mm, this is perfect as the bed is 160mm deep, my cubes are 75mm deep so the water level is 10mm under the rockwool so as not to keep too wet. i reckon you should be fine with a pump that size, if anything the backpressure coming from the 4mm hoses will make the pump work a little tougher just to push it through, so dont worry about it 'not' having enough power.
Now as for dealing with aqua-wholsaler or whatever they are called...i am just coming out of a dispute with them. and also two of my buddies from the states have had drama's with them before...dont get me wrong they have good products just fucked with shipping....(they never send it untill you fight with them)
heres what happened with me....i ordered an air pump at $25 and 25 shipping.....it has never arrived!!!! --- well they were selling top rate shipping but using the free trade agreement with S.E Asian and Aus to send FREE small parcels, they thought that i wouldnt pick up onnit. well after 5 1/2 weeks i sent them a nast email...they backed the fuck up and opologised and re-credited me and then i aske for a free 1000L/H pump and they sent it in a jiffy, 7 days-is all it took....so yeah i called their bluff and it worked double well for me. thing is tho i dont need the imersable pump i need the air pump!!!!