View Full Version : adding a 2nd return line to AGA tank

09/17/2008, 06:07 PM
alright i am planning out my plumbing from the basement to the 90 gal AGA corner overflow. i have been told the 1" drain on these will only flow 600gph'ish.

to get more drain flow, i am considering using the 3/4" return hole as another drain, and in the other back corner drilling a hole for a 1" bulkhead as my return spot.

any insight on if this will be a problem or not?

the return pump is a Little Giant 4mdx, at 11' it would only push 490gph thru 3/4" pipe, i know i could get a bit more flow if i ran 1" and then adapting before and after the 3/4" bulkhead, but i dont think i would get the same as if i just ran a seperate 1" return.

09/17/2008, 06:54 PM
Sounds good.
You could also look into getting a Sea Swirl for the return instead of drilling a bulkhead.

09/17/2008, 07:32 PM
First off, I think 600 GPH is plenty of return flow and then some. Second, the long drop of a basement sump will allow more flow than a short drop. You can increase the diameter of the drain plumbing to increase flow as well. You may have to modify the overflow weir to allow more flow through it.

09/17/2008, 08:05 PM
the seaswirl wouldnt help me out, i dont want anything on the backside of the tank.

the drop of the basement is going to make more flow, the diameter of the pipe determines that. increasing the diameter will help some, but like the return, the bottle neck is going to the bulkhead.

the weir would be modified by not having the return loc-lines.

my concern is the glass having an extra hole in it.

09/17/2008, 08:08 PM
The long drop increases velocity. The water is travelling faster when it has a bigger drop. It "pulls" more GPH. Like the return, a momentary decrease in diameter from the bulkhead is very minor in comparison to the entire length of the plumbing and has only a minor effect.

09/17/2008, 08:37 PM
on my oceanic tank i used all 4 holes for drains and have a seperate line for the return, i wanted to have plenty drain, what you have planned out should be fine, sounds like you want to have both holes for your drain, i have 8-10' to my basement sump, like Sjm817 had said the velocity is very high therefore i had to place gatevalves on 2 of the 4 drains to prevent so many bubbles in the sump. i then have the other 2 as emergency drains, i have more then enough for drains.

09/18/2008, 12:01 PM
I checked with 2 Civil Engineers.

Both said that head pressure(the amount of water above the drain) and the orifice diameter control the amount of flow, not velocity.

Even ran it thru a program to determine that same outcome.

09/18/2008, 12:13 PM
<a href=showthread.php?s=&postid=13377516#post13377516 target=_blank>Originally posted</a> by DodgeDude99

head pressure(the amount of water above the drain) and the orifice diameter control the amount of flow, not velocity.

With this information that more head above the drain will increase flow, how do you think that relates to your question? Do you still think a longer drop to the basement wont increase flow?

09/18/2008, 02:35 PM
the longer drop wont, 2 civil engineers confirmed that.
its the water pressure above the drain that increases flow.

i dont want to rely on the weir filling up with water above the drain pipe to increase flow.

having the second drain was also meant to be a safeguard if something gets clogged in the other.

09/18/2008, 03:26 PM