Best overflow method for most flow?

[reeftank21]

I have an 1 1/2" bulkhead in my overflow. I currently operate with a durso standpipe. I'm trying to us a dart for my return pump but it can't get enough water to pump. I realize that this seems excessive flow for my return pump but I would like to use it anyway. Any other types of standpipes that allow for greater flow? I'm really only hoping to get about 1500 gph.

[kgross]

How far below the waters surface is your bulkhead? Even with a 1.5 inch bulkhead on an overflow unless it is the bottom of your tank and you can build up a foot of water or so for head pressure it will be very hard to get that much flow. What I would do if I was you, use the DART as a closed loop pump and get the full 4000gph out of it, and use a 1000 to 1500 gph pump for your return.

Kim