what size barb to match Eihm 1250 inlet?
 

I want to build my own resevoir and I would like to not use a reducer on the 3/4" or is it 5/8" inch inlet on the Eihm 1250. Can anyone tell me me what would be the correct size to use? I know that I can get the part from macmaster but to make it simple for me how about the current correct part number? Also would I need 3/4" or 5/8 " inner diameter tubing to connect the resevoir to the pump?Thanks for your help in advance John

I think its 5/8 OD, however I just force my 1/2 Tygon over it. Since the barb ID is roughly 1/2 inch anyway, you won't be restricting it any with 1/2 Tygon.

Thanks
 

Thanks I didn't think of that inner diameter limitation of the pump intake fitting.

The intake fitting on the 1250 is made for 3/4 ID tubing and the threads are 1/2 NPT.

correct size
 

I checked here and at the Eheim wedsite and they state that the intake barb outer diameter is 17mm and the output barb outer diameter is 13mm. So if I multiply 17 X 0.0394 I get .6698 inches. If I divide 5 by 8 I get 0.625 inches. So it seems that the best size tubing I can buy to connect the 5/8 inch barb from the resevoir would be the 5/8 " It looks like the 3/4" would be to large. I am wondering though why the 1/2" tygon seems loose on the original ouput barb on the pump as some people have reported on this forum because when you multply the 13mm stated by Eheim for the output size you get 5.122" that should make a nice tight fitting. Is the barb smaller than 13 mm or is the Tygon 1/2" a slightly lager inner diameter?

I had trouble with my 3/8" silicone tubes and an adapter for my rad. The tube didn´t fit tight enough with less than 16 mm hoses. So a 1/2" tube sitting loose on a 13 mm hose shouldn´t be impossible.
Eheim states 17 mm, 3/4" on the site.
http://www.eheim.com/technik_pumpen.htm
regards
Mikael S.

3/4 ID? Thats huge! I'm sure the ID is about 1/2 and from the Eheim site it looks like I'm right. I also don't think the threads are NPT.

I have the eheim 1250 and some 3/4 ID clearflex tubing, and trust me:), that tubing fits on the intake fitting. It is not a tight fit, but the fitting makes contact with the tubing all the way around. As for the threads not being NPT, right you are:D. They're another type of thread, but I can't remember which. However, 1/2 inch NPT polypropylene hoses barbs fit very nicely. FYI, for the output fitting I'm using 3/8 inch NPT, which also works well.

yeah, at first i thought the inlet barb was huge compared to the 1/2" clearflex60 ID from cooltech. it takes a little massaging, but it'll fit. you don't need to buy a replacement.

after getting a small piece of the barb in the tube, the trick to get the rest of it in (from what i learned) is to push in with the tube then and to one side. continue to do this from one side to the other.

[edit]
ok. i guess explaining it with words isn't my forte, but these videos should help

attaching (i didn't put it all the way in, but you get the idea)
removing

(quality ain't that great since i used my webcam to make em. you'll also need divx codec to view them)

here's a pic of the attached hose
http://geeksupport.com/images/forums...nlet_eheim.jpg

check out my thread about the eheim barb sizes.

i dont own an eheim, but i think the other kind of threading u r talking about is like BPT or BPST or something!

thanks for the help one more question
 

I noticed when I checked your thread about barb sizes that D-Tek confirmed that the tygon was a little loose at the output when using the stock Eheim barb and said they would make new ones available that was back in June has anyone heard anymore about this? I didn't see any special replacement barbs at their website for the output. That is why I did the math and converted the 13mm to 0.5122" to check and see if it should fit tightly there. I wish that at least D-Tek or someone could identify the correct size completly such as 1/2,3/8 bsp or whatever the correct size is.

yeah, i just noticed that too. i dunno why they said it was a little loose as you have to really force that sucker on the inlet barb. if anything, it'll be even more loose by replacing it with a 1/2" barb. it was a lot easier putting the tubing in the DTek Pro Core, Maze4 GPU Block, and DTek WhiteWater 1/2" barbs than it was with the eheim inlet barb.

check out the picture at the end of this article.

[edit]
oops, you said outlet, not inlet. yeah, it is looser/smaller compared to the 1/2" barbs. i tried to find a replacement for it but couldn't find any fittings that would make the outlet 1/2" ID at Lowes or Home Depot (they only had 3/8" ID fittings). you can pretty much stick the outlet barb into the inlet barb. i dont know who's bright idea it was to make different fitting sizes for in/outlet.