Proper tubing size to use with an Eheim 1250

I'm considering using an Eheim 1250 in my theoretical water cooling system. It's obvious from looking around here that 1/2 seems to be pretty standard. One fitting on it is 3/8 and the other can handle 1/2 or 5/8. Is the 3/8 fitting the intake side of the pump? With a barb change will this accept 1/2 tubing without horrible flow restriction? I'm hoping that the 1/2 (or 5/8, heh heh) fitting is for the output, cause from the Simple Danner3 and Eheim 1250 test it seems that running 5/8 is the way to go with this.

If you read that thread again you'll see that it says the intake is 5/8

So the intake side of the pump is 5/8 and then the output is 3/8?

Normally people convert the output to 1/2 correct?

Would they're be an advantage to run 5/8 output?

Thanks, again.

seems to me mine has a 5/8 inlet and a 1/2 inch outlet. . it's worked that way for increased intake, higher velocity through the 1/2 inch outlet. 1/2 ID inch tubing will go over the 5/8 inlet just fine. This will prevent u having to use any reducers later in your tubing, for the block or anything, which is not recomended.

1/2 inch id tubing is your best route, imo.


J.

The pump's inlet and outlet are specified as follows:

Hose connection (suction side) Ø17mm (3/4")
Hose connection (pressure side) Ø13mm (1/2")

1/2" ID tubing all around would be fine. Remember that flow rate is a lesser factor in watercooling performance after a certain point (which you pass with an Eheim 1250 easily).

I think the official specs refer the the diameter of the threaded pipe part of the barbs you screw into the pump. If you take a ruler and measure the inside diameter of the stock plastic barbs that come with the 1250, the intake measures .5 inch ID and the top outlet starts at .5 ID and tapers up to .375 inch. I am concerned that there be .5 ID system-wide, so I replaced the outlet barb with a 2 inch long .5 ID brass threaded pipe connection. I am tempted to replace the intake barb with a .625 inch pipe connection as well to ensure adequate draw from the res.

Jibjo said:

I think the official specs refer the the diameter of the threaded pipe part of the barbs you screw into the pump. If you take a ruler and measure the inside diameter of the stock plastic barbs that come with the 1250, the intake measures .5 inch ID and the top outlet starts at .5 ID and tapers up to .375 inch. I am concerned that there be .5 ID system-wide, so I replaced the outlet barb with a 2 inch long .5 ID brass threaded pipe connection. I am tempted to replace the intake barb with a .625 inch pipe connection as well to ensure adequate draw from the res.

Click to expand...

Can't verify that right now, my 1250 is in use... it would mean their own description ("hose connection") is off then.

FIZZ3 - I know, I was a little annoyed that the outlet barb looked so skinny compared to my tubing so I grabbed my kid's ruler. I should receive my block any day now and will compare flowrates between stock barb and the larger one.