Have I sized my return pump and overflow right?

[classic-chassis]

200GAL tank. Drilled with a 25mm overflow.
60GAL sump (will be about 40GAL full of water when running).
Tank has a 25mm return hole at the same hieght as the overflow but I will reduce pipe size to 18mm from the pump.
pump size 1270gph Hmax14.8 feet.
Not too many twists in the plumbing.
I want the water to be cycling enough for Arowana.
I

 

[justin guest]

I´d do a second 25mm overflow. A good rule of thumb is that the diameter of the overflow should be double the diameter of the planned return assuming the return is sized sensibly to the pump.
j<><

 

[classic-chassis]

Obviously the retrun pump i bought is not powerful enough because on filling last night i nearly flooded the living room.
I need to upgrade, but that means there is more than 1270GAL of water comming out of the 25mm overflow.
The pump i have is big. the next size up even bigger. And bigger and it won't fit in my sump!

 

[chesterthehero]

if your overflow is overfilling your sump... you have too much water in the tank/sump..

start by filling the tank below the overflow level.. then add some water to your sump.. then turn on the pump... the water level in the tank should even out at the level of the overflows and the sump will then level out minus the water than went into the tank/whatever evaporates durring the day

 

[classic-chassis]

I was thinking that last night, but i'd been workingt on getting it up and running all day.
I'm going to try again tonight.
The problem is though the overflow hole is at the top of the tank (at the normal hight of an overflow box)
and it made a lot of noise as it was sucking air as well as water.
I think i need to modify the overflow buy putting a downward 90 degree curve on it, so that the overfolw enterance is always under water.

 

[rallysman]

if the pump is raising the level above your overflow then the pump is too big. If you can circulate 600-800gph through your sump then you should be alright. if you need to slow your pump down you can put a ball valve after the output of the pump to reduce flow.

 

[chesterthehero]

I think i need to modify the overflow buy putting a downward 90 degree curve on it, so that the overfolw enterance is always under water.

doing this will work and help with the noise.. however if you lose power it will drain itself till it loses suction.. but once power comes back it will not start again.. which will then overflow your tank

post a pic of your setup.. or a drawing if you cant see it (post it anyway we like looking at other peoples tanks)

also search for dorso standpipe...
and check out this thread

 

[classic-chassis]

Cant post pics right now there at home on my camera.
I'm only talking about a plastic pipe curve section.
The in flow is built with a 90 degree curve pipe and it has about 6 inches from the bottom to the inlet hole.
When i filled my tank water started to fill the sump through the unpluggeg pump like an overflow, so it must restart if the power goes out.

 

[classic-chassis]

if the pump is raising the level above your overflow then the pump is too big. If you can circulate 600-800gph through your sump then you should be alright. if you need to slow your pump down you can put a ball valve after the output of the pump to reduce flow.

that isn't the issue, the issue is too much water draining into the sump and the pump not pumping enough back, so the sump nearly overflows.
Chesterthehero pointed out i may be over filling the tank, which i was doing to try and stop the gurggling (the overflow is a hole on the back pannel at the top.) by raising the water level to submerge the overflow.

 

[classic-chassis]

Thanks cth I followed you insruction and got things running.
I also put a 90 degree pipe fitting on but instead of pointind it down (ths drained the tank to the level of the bottom of the pipe.) i tunned it to the side. it still noisy though so I'm trying to figure how to make it quieter.
It also has a lot of power so i think i need to build a PVC box around it full of holes to protect the fish.