DIY Overflow: What am I doing wrong?

[paragoned]

Sorry, I didn't know you were so thin skinned. I wasn't trying to insult you, nor was anything implied. I was having fun with Pharaoh, that is all.

And to be insulted because "I'm implying that you are wrong", wouldn't that make you a Know-It-All? Secondly, I wasn't implying it, I was stating it. You are wrong. You can not put that water volume through that pipe under gravity. I corrected Pharaoh, but he wasn't insulted. There was no reason for him to be.

*sigh... wow.
First off, I didn't say you implied I was wrong. You implied I didn't know the simple fact that 3/4" wouldn't flow that much. And under different circumstances, I wouldn't have taken offence. But in my original post, not only did I suggest that I already knew that, it was my whole basis for trying to explain my real problem.

If someone asks what 2+2 is, you don't tell him what 1+1 is and imply he doesn't know. That's why I was insulted. I took it as a blatant disregard for what my actual problem was.

So I apologize for not making it clearer, if that's the case. So let me try again, and we can end this.
The 3/4" is immaterial if not for the fact that I was using it as an indication that the 1-1/4" wasn't flowing enough. You'll agree that the 3/4" doesn't flow more than a 1-1/4" right? Of course! That's how I knew I had a flow rate problem! If the 1-1/4" siphon was capable of flowing more than the 3/4" drain, then why the hell wasn't water building up like it should when it reached the 3/4"? I was getting piss poor flow. So low that the 3/4" had no problem keeping up with it.
Get it?
I never said I wanted to use 3/4" to flow 840g (why the hell would I build it at 1-1/4" then?) nor that I WANTED as much as 840g (I was only trying to give details about my pump.)
I merely said, "I don't think my 1-1/4" is flowing as much as it should, here's why I think that..."

Hopefully that's a little bit clearer. And you can hopefully see why I took insult. Seems like a misunderstanding and I should've seen it before getting hostile.
As for the know-it-all comment. I'm not the one who insisted on being right without even know what the problem was.

And for the rest...

Wow, you're really gonna be pissed at this: you are wrong. Way wrong. I'll let someone else insult you with the reason why.

I'm sorry if I don't understand. You're actually telling me I'm wrong about the size of my own pump's return line?

The only reason the inlet flows at 840gph is because there is a pump behind it.

Exactly. But I'm not the one who said "never".

No one said to extend the vent tube.

Sorry, I meant why is there EVEN a vent tube in the design? Why not just end it at the tee (and leave the top open)?

bingo i have to agree with chompers and pharoh

Hey, so do I. That wasn't my problem though.

 

[Pharaoh]

The misunderstanding occured when you assumed that the 3/4" hose on the overflow doesn't matter. The 3/4" hose IS constricting the flow. The vent tube does not fill up based on the exact reason you gave. The force of the water weight pushes downward and increases the flow. If you changed the hose on the "T" to 1 1/4", you will see immediate improvement. The amount of water flow you have will be directly proportionate to the smallest diameter in the system as I said once before.
The vent tube is there to eliminate the buildup of air pockets in the system and to stabilize the siphon.