Issues with plumbing overflow for Nano tank

[SaltySquid]

This is from another post I started but hopefully someone can help me figure out a solution to this issue with my overflow not working:

Ok so I decided to build an overflow for this but am running into a few problems. Once i prime the system I have to cap the vent to keep in order to keep it going. So I'm guessing it's running by siphoning. It also only restarts if I do a short break in water flow. So needless to say, as it stands this is going to cause my living room to flood. Does anyone have advice on how I can fix this to work correctly and not have a flooding potential.


So just found out that if it drains to fast from my display (homer bucket) to the sump (tub) the draining stalls and causes flooding as well..;Rage

 

[hijinks7]

can you post a pic of what it currently looks like?

 

[SaltySquid]

The pics should have been in the original post....sorry, here they are. I think part if the problem is I forgot the final U going into the tank, but I still fear that even fixing that I may still risk an over flow if the main system after the drain is interrupted for any length of time.

How far into it above the sump should the drain line be placed?

And I chose this size pipe because I'm running 3/4 for the supply and wanted a drain twice the size of my supply. But I'm open to any suggestions. I'll even build or buy something else if its a better solution. I just need to do something that doesn't break the bank or involve drilling my tank.

 

[SaltySquid]

So how far into or above the sump should the drain end?