I have 2 x Tunze 6045's in my 1700 x 600 x 600 tank and that combined with the return pump gives me more than enough flow , the 6045's are not controllable , you can dial them back a bit with the blue sleeve that you move up and down .
I found that if you want controllable Tunze's they jump up quite a bit more , hence I "settled" on the 6045's and have been quite happy with the result.
Ideally I would have liked to have gotten the Ecotech Vortech MP40 but at around $ 800 its quite a bit to lay out :fshi:
I also got my gravel from Stone and Water World on Marua rd , I got 1-2mm Black marble chip and was quite happy with the result , I mixed 1 bag of the Chip with 2 bags of Cichlid mix