If your worried about price then go for the Rio pumps. I am going to use two of them in my 220 setup and should be getting around 1,600-1,700gph after head loss. I bought three Rio 20HF pumps for $60 each on Amazon. I will use two in my setup and keep the third as a spare, and to pump water out/in during water changes.
I don't think one of those pumps will be enough for your entire tank on its own. You will need another one and since you can't return that one, just add a Rio as the second pump. It should put your flow right where you need it when combined with the Little Giant you already have.
The plan to "extend" the tank needs to be thrown out the window. There is no way that will ever be reliable. In addition, you will be adding about 3-4" of water height to your glass tank that wasn't designed to go over 24" tall. I wouldn't risk that kind of additional pressure on the main tank glass. If that is the only way your dad is willing to set the tank up with the sump, then forget the sump and stick with canister/HOB filters. You can still build a DIY canister using the Little Giant pump if all else fails. If you guys don't want to drill the tank, then I recommend using a HOB overflow. You can get the kind that use a small suction pump to suck the air out so that the siphon can be re established if lost.
If you decide that you want to try to drill the tank, then you can go with an overflow setup that goes through the back wall of the tank instead of the bottom.
Take a look at my overflow setup. If needed, this could be done with the tank still setup. Just drain the water down far enough and drill from the outside of the tank so that the glass doesn't run down into the tank. It will still be pretty messy but you shouldn't have any trouble getting it cleaned up when you're done. You don't need to drill holes for the returns, you can just run them over the top of the tank.
Just an FYI, I am using three 1.5" gravity overflows, rated for 1,200gph each, for a total of 3,600gph of total flow capability. This is so that I have over double the drain capacity for my desired flow, which means that if one of my drains were to ever get clogged, my system won't overflow.
I don't think one of those pumps will be enough for your entire tank on its own. You will need another one and since you can't return that one, just add a Rio as the second pump. It should put your flow right where you need it when combined with the Little Giant you already have.
The plan to "extend" the tank needs to be thrown out the window. There is no way that will ever be reliable. In addition, you will be adding about 3-4" of water height to your glass tank that wasn't designed to go over 24" tall. I wouldn't risk that kind of additional pressure on the main tank glass. If that is the only way your dad is willing to set the tank up with the sump, then forget the sump and stick with canister/HOB filters. You can still build a DIY canister using the Little Giant pump if all else fails. If you guys don't want to drill the tank, then I recommend using a HOB overflow. You can get the kind that use a small suction pump to suck the air out so that the siphon can be re established if lost.
If you decide that you want to try to drill the tank, then you can go with an overflow setup that goes through the back wall of the tank instead of the bottom.
Take a look at my overflow setup. If needed, this could be done with the tank still setup. Just drain the water down far enough and drill from the outside of the tank so that the glass doesn't run down into the tank. It will still be pretty messy but you shouldn't have any trouble getting it cleaned up when you're done. You don't need to drill holes for the returns, you can just run them over the top of the tank.
Just an FYI, I am using three 1.5" gravity overflows, rated for 1,200gph each, for a total of 3,600gph of total flow capability. This is so that I have over double the drain capacity for my desired flow, which means that if one of my drains were to ever get clogged, my system won't overflow.
