Self Starting Siphon on Overflow

rainfishy

rainfishy

Member
Hi, I'm still working on my DIY HOB Overflow box and I think I've spent two weeks straight reading all the info on this site! But I still have two questions
1) How do I make the siphon tube self starting? my design includes air tubing to start the siphon. But I would prefer that it be self starting.
2) What breaks a siphon? Obviously i would assume that lack of water would break the siphon, but what other things can cause a siphon to break?
OK I lied, I have one more question
If the siphon breaks, and my return pump (from sump/fuge) continues pumping it will overflow my display. How can I prevent this? I have heard or read that drilling a small hole in the return line right above the water line will make the return pump stop if the display water level gets to the hole. Is that right? If so could someone explain why that will prevent overflow of the display tank.
Thanks so much
 
farmboy

farmboy

Active Member
I'm not sure about self starting. Maybe a vacuum pump like on CPRs?
Both ends of your siphon tube should always be under water-no matter the level in the display. Air bubbles collecting over time can break the siphon.
The return will run dry. So however much water is in the pump section of your sump will end up in the main tank.
The little hole in the return line from the pump is to prevent siphoning of that line back down into your sump in the eventof a power outage. That could be a LOT of water depending on where your return is inside the display.
Hope that helps.
 
squidd

squidd

Active Member
1. Once the siphon is "established" IE: the U tube is full of water and both ends are submerged in their respective boxes (inner and outer) The siphon will "start" automaticly any time the water level in one chamber is higher than in the other...and water wil "transfer/siphon" to the lower level chamber
2. The trick is to keep the U tube full and not allow bubbles to build up inside which can "slow" the siphon rate or even "break" the siphon if their is enough air to keep water from transfering...
2b. A float "switch" can be set in the sump to turn the pump off when the water level gets too low (pumped up and not returning), or a float "switch" can be set in the tank to turn the pump off if the tank level rises too much...
2c. The hole you discribe is an anti siphon hole and usage explained correctly by Farmboy
 
You must log in or register to reply here.
Top