overflow/sump confusion

[Jandree22]

One thing I've been baffled about ever since I started this hobby years and years ago, is how sumps and overflows work. While I think I finally figured out the main aspects of the way these both funcion, there are two things that still confuse the heck outa me...

 

1) I think I know the answer to this already, but I'll ask to be sure. Which should have a slightly higher flow rate... the overflow or return pump? I thought the overflow should be so the return pump isn't constantly running dry in the sump. Am I right here?

 

2) In the event of a power failure, won't I lose the siphon of an overflow? Because I have tempered glass on my 75gal I can't drill it and have to make a HOB overflow.

Okay... now I understand the water will stop siphoning out of the main tank once it gets lower than the inlet of the overflow. BUT, won't the remaining water continue to siphon out of the bottom of the overflow box until it hits air(stopping the siphon)?

 

If those two questions are confusing, especially #2, I'll try to re-word them...thanks for your help tho!

 

~Joel:happy:

[Jandree22]

nm... I just figured out #2:happy:

 

If anyone has any thoughts on #1, though, I'd still appreciate any input!

[offsprg01]

put a flow valve on the return line and the siphion line. this way yu can adjust and fine tune till your hearts content. but if one isgoing tobe higher than the other you want the siphion side to be higher.

[Jandree22]

yup, two ball valves were in the plans:) thanks!

[reef93]

1)The flow rate of return pump and overflow MUST be equal, otherwise it will flooding. Make sure you overflow able to handle the return pump. an U-tube(1") handle about 350gph.

 

2)Depend on the design of the overflow box, if this DIY overflow box with two boxes and u-tube = FLOOD. There should be a baffle in each overflow box seperate the u-tube outlet to drain pipe. check this site for picture.

http://lifereef.com/frame.html

 

I had ameracle overflow over almost two years and never had a problem with it when power failured(numeric times).

 

HTH

[Jandree22]

Originally posted by reef93

1)The flow rate of return pump and overflow MUST be equal, otherwise it will flooding.

 

How so if the overflow was flowing more than the return pump?

[offsprg01]

the over flow needs to be able to handle more than the return pump can throw at it. it won't be able to let out more water than is pumped it if it is plumed right.

[reef93]

i was little confused at first.. yes, overflow(u-tube) and drain pipe must have higher flow rate that pump.

[Jandree22]

k, I finally think I understand... thanks guys:D

[skeletor]

you can also put a check valve in the return like to stop the return from syphoning back into the sump, in the event of a power failure.

 

-skeletor-

[skeletor]

something else you might want to consider is a float switch to shut off the return pump in the event that something happens to the overflow (ie snail)... If the overflow stops and the return pump is still running you could overflow the main tank. This depends on the volume of water in the return chamber of your sump, the water level in the main tank and how much you care about running the return pump dry.

 

-skeletor-