300g Powerhead placement help

[karak]

Hey guys, I have a 300g 8x2x2.5 set up for about 6 months now, and I'm starting to notice poo accumulating on the sand. Here is a little pic of my set up


The green things are fake plants that have been added.

I dont do much vacuuming from the bottom when i water change so i was wondering where effective places to put a wavemaker(s) type power head to help stop the poo from settling on the bottom of the tank and make its way into the over flow.
The return is ~1400gph

Thanks for any advice

 

[Ancient_Fish_Master]

top right corner pointing down.

 

[karak]

What size pump would you recommend?

 

[Ancient_Fish_Master]

id go for 1000 or more gph