why dont people use siphons?

[Matt181]

ive been thinking, why dont people use siphons as overflows?

i know obviously if you put them at the bottom of the tank and dont have a hole put in it then its going to drain your tank in a powercut but surely if there was a hole at a set level in the tank to allow air in, it would stop the siphon?

if you went on one of the volume calculators and measured how fair down the hole was you could work out how much water the siphon would take out before the hole allowed air in to break the siphon?

just a thought
Matt

 

[kzimmerman]

People do, and it cause floods because of the hole being plugged, or a too small hole, ect. Just smarter to use an overflow box, which actually does use a siphon.

 

[kjfan1]

Great answer.

 

[ShabbonaJim]

ive been thinking, why dont people use siphons as overflows?

i know obviously if you put them at the bottom of the tank and dont have a hole put in it then its going to drain your tank in a powercut but surely if there was a hole at a set level in the tank to allow air in, it would stop the siphon?

if you went on one of the volume calculators and measured how fair down the hole was you could work out how much water the siphon would take out before the hole allowed air in to break the siphon?

just a thought
Matt

Because when a siphon breaks, it doesn't restart. An overflow uses a siphon, but if the flow stops, it equalizes the level on each side, and when flow returns, the siphon process continues.

 

[Redoog]

I basically use a siphon. You need have enough storage in the sump though. Sump needs to hold the amount of water that the tank will lose before the siphon breaks, so that when power comes back on, it fills the tank, and the siphons starts up again.

http://www.monsterfishkeepers.com/forums/showthread.php?t=262743&page=1

Mine has been tested several times. Tank drains about 3" til it gets down to the holes i drilled, then everything stops draining.

Or an auto-topoff, which i will be adding as well, will only work when power is on, so no porblems during power outs, and everything restarts when power is back on.

 

[FSM]

A siphon is not an overflow. A siphon only forms if the max drain rate is equal to or less than the pump output. You have to have some air going in too, so if more water is added, the flow rate of the drain can increase. If the flow rate of the siphon is more than the pump, the water level in the overflow will fluctuate; a siphon starts to form, which quickly empties the overflow, and then the process starts over as the overflow fills up again.

But, you can use a siphon as the primary drain, with another standpipe or whatever as a backup, to pick up the extra water that the siphon can't keep up with. Air in the mix is what causes all the noise problems.

 

[TheCanuck]

I'll give you 1,000,000$ if you make a syphon that can perfectly match a return pump and have it work correctly for more than 2 hours.

It just doesn't work, if you own an overflow or sump you would understand.

 

[Cashlaw]

I dunno . . . I've used PVC siphons into sumps before. You just put the top intake opening of the siphon inside the tank, at the level where you want the siphon to shut off. The siphons don't usually stop working unless the water level evaporates off too much, or the pumps fails, or something like that. The trick is to give the siphon way more capacity than your return pump, so that air bubbles and things like that don't clog it.

 

[Matt181]

Great answers, thanks guys i guess i was being dumb!!

looks like an overflow is going to best

btw anyone had any experiences with wiers?

Thanks
Matt

 

[redtailshark1]

People do, and it cause floods because of the hole being plugged, or a too small hole, ect. Just smarter to use an overflow box, which actually does use a siphon.

Sorry i wish not to agree, overflow boxes do not use siphon, they use the gravitational water level corrections and the gravitational weight of the water pulling it down the tube