Pump for 180g calculation, input needed

Hello everyone,

I have been calculating the GPH from DT (180g) to sump (60g), to find out which pump would be best.

The tank has 2 overflows drain and 2 returns. Drain holes are 1 3/4 and return holes are 1 1/2. From what I research, with the bulkhead, it will become 1 inch drain. That means it will drain about 800-1,000 gph. Since it has 2 drains, it means it will drain 1,600-2,000 gph.

From what I read, I need about 6 to 10 times the tank's volume. This means about 1,080 to 1,800 gph. That's basically the pump that I would go with as it won't return more that it drains.

Then I call my LFS, the guy told me that I need 15 to 20 times since I will have corals. How is it possible? That means I need 2,700 to 3,600???. It doesn't seem logical to me as the drain only 1,600 to 2,000 gph.

Anyone has any opinion on this? Is my calculation wrong?

Thank you

 

That is a lot of circulation. Perhaps you will be able to achieve that with power heads in the DT helping push the water around.

 

you'll need a couple powerheads at least to get enough flow. And IMO, 15 to 20 times is only enough flow for softies and some LPS, you'll prob want closer to 30 times actually and 40-70 times for SPS.

Look into these if you have the budget:
Ecotech Marine Vortech Propeller Powerhead/Pump

or these are what I have and like them, and are much cheaper;
Hydor Koralia Evolution Circulation Pump/Powerhead

and look into getting a wavemaker for them

 

Thank you everyone. So should I go with 1,600 - 2,000 gph or lower? I will have power heads for sure. I am just trying to get the pump at the moment.

 

I'd get the bigger one and install valves on your return line to drop the flow rate down if needed. That way you know you have as much flow as you can, instead of being underpowered, IMO.

 

Well, that comes back to my first situation. The drain supposedly only drain 1,600 to 2,000 gph. Pump that has more than that will spill the DT, don't you think?;D I guess the valve will help

 

No, you can put a flow restrictor on your return lines to lower the flow to where you want it. Just a basic plastic valve from Lowes works. Install it inline from your pump and you can then adjust the flow to where you want it.

 

Get the pump thats rated at 1500-2000gph at 4-5 foot of head and put a gate valve on the output. With that gate valve you will control how much flow is going through the pump, then you can slow it to wherever you are comfortable.

 

Thank you so much for your input everyone. Here goes the pump hunting.

 

I have the same set up as you. I run between 3-5x turnover through the sump and about 36x in the tank with the powerheads. The pump I'm using for a return is a Mag 18. Since it is a FOWLR I am using 2 koralia mag 8s. depending on the corals that you want to keep, you could go as high as 70x or more. You want less flow through the sump so that the skimmer and other filtration can filter the water more efficiently while the powerheads provide water movement within the tank. If you do a closed loop, that's a whole different story.