Water flow and sump help

[brigoody]

I'm just setting up my very first SW tank for FOWLR. I bought a 90gallon with built in overflow, and I will be using a 15-20gallon Coralife sump with a Berlin protein skimmer and Rio 2500 pump.

My confusion is with the water capacity and flow rate. I have a 2" bulkhead for the overflow and 1" bulkhead for the return. No pipes yet. I've read many articles, but I am still confused on how much water should be flowing out and how fast should the return be. I'm pretty sure that less water should be returning than overflowing right? Do I determine the return rate by the Rio 2500 and how long the hoses are? If so, then how do I determine how fast the water is overflowing to the sump? I read things about figuring out the capacity of the drain pipe, but since that bulkhead is larger, I'm just not sure how to figure all of this out.

I just don't want to make any mistakes.

Any help to this newbie is greatly appreciated. I've included a picture of the built in overflow

[MACATUA]

The drain will automatically drain at the same rate as the return pump, unless the flow is to great for the overflow to handle. I just built my first sump, and had the same worry, but if you have enough drainage to account for the return pump, it really is very simple.

Just make sure your overflow can handle the rate of the return pump and all is well.

HTH

[brigoody]

You do make it sound pretty simple, but how can I figure out the rate of my built in overflow? I know the specs for the rio2500 at 4ft. is a little more than 500gph, and that most HOT overflows are between 600-900gph, but how do I determine the rate of the built in?

Now, since I have a 90gallon tank, I figured this pump would be fine if I use the general rule of moving water 5 times the volume of tank; however, if the rate of my built in overflow is very high, is this pump going to still work?

THanks for the replies

[MACATUA]

You can always supplement flow with powerheads.

Trial and error on the flow, you should be more than ok though. Just watch it closely when it fills, once it starts to drain into the overflow, just make sure the water level stays constant. If it rises above that and keeps rising, you don't have enough drainage. That being said, I don't think that with that pump you should have any problem with a built in overflow.

[brigoody]

Thanks Macatua. I also just got back from a LFS, and the guy there confused me even more. I thought I needed a "J" drain pipe that would connect to the bulkhead and then send the water to the sump.

If you look at my picture, the smaller box is the overflow and I am assuming the larger is called the reservoir. Once the water rises in the overflow it will go into the reservoir, but then don't I want the water to rise in the reservoir and drain through a "J" drain pipe. The LFS employee made it seem like I just need the bulkhead since my tank is drilled in the bottom.

Thanks

[brigoody]

Correction. I guess the drain pipe I am thinking I need is called a standpipe. Do I want to use this in my reservoir so the overflow is not dropping all the way down the tank before it goes into the sump?