noob wet/dry quetion

[IrnGynt]

I'm considering a wet/dry trickle filter for a 75g I'm setting up. Thing is, I've never used one before. I've always used HOB or canister filters as wet/dry's have always seemed a bit complicated to me.

Question has to do with flow in and out of the filter. You have a fixed flow rate in through the overflow then you have a fixed flow rate out with the pump. If the outflow isn't adjustable wouldn't the sump either go dry or overflow eventually if the two do not match exactly?

 

[Iffrat]

I'm considering a wet/dry trickle filter for a 75g I'm setting up. Thing is, I've never used one before. I've always used HOB or canister filters as wet/dry's have always seemed a bit complicated to me.

Question has to do with flow in and out of the filter. You have a fixed flow rate in through the overflow then you have a fixed flow rate out with the pump. If the outflow isn't adjustable wouldn't the sump either go dry or overflow eventually if the two do not match exactly?

as long as the overflow can handle the return pump then it will equal out to the return pump .. say 1000gal/hr return ... the over flow is 1200gal/hr ... the return puts water back into the tank and the overflow runs at 1000gal/hr ..

make since?

 

[Iffrat]

i dont know if that even made since to me .. lol

bottom line is the overflow has to be capable of more flow then the return pump can put out ... as long as that happens then the whole system runs at the flow rate of the return pump ..

 

[Dragonflyx2]

i dont know if that even made since to me .. lol

bottom line is the overflow has to be capable of more flow then the return pump can put out ... as long as that happens then the whole system runs at the flow rate of the return pump ..

what he said, the second time. lol

 

[Burko]

Heh...It makes cents to me.

"You have a fixed flow rate in through the overflow "

This is the flaw in the OPs thinking cap.

 

[IrnGynt]

Thanks for the quick response!

So basically I just have to make sure the pump doesn't exceed the overflow's maximum recommended rate.

I still don't grasp how the two flow rates "equalize". But now that I think about it, the overflow's limiting factor wouldn't allow the sump to overflow. Kind of like, flow then stop and let the pump catch up. At least that's the way I envision it.

Probably make more sense once I set one up and see it in action.

 

[Iffrat]

Thanks for the quick response!

So basically I just have to make sure the pump doesn't exceed the overflow's maximum recommended rate.

I still don't grasp how the two flow rates "equalize". But now that I think about it, the overflow's limiting factor wouldn't allow the sump to overflow. Kind of like, flow then stop and let the pump catch up. At least that's the way I envision it.

Probably make more sense once I set one up and see it in action.

the overflows auto regulate to the water in the tank .. so as long as the water is not coming back into the tank faster then the overflow can handle ... the overflows are good to go


so if the pump is doing 1000gal/hr and the overflows can do UP TO 1500gal/hr then the overflows only do 1000gal/hr ... you dont have to regulate it .. it happens all on its own to the speed of the return pump ..

 

[Burko]

"Kind of like, flow then stop and let the pump catch up. At least that's the way I envision it."

More like, flows evenly at maximum tank level, determined by the height of overflow. And allow room in sump for power outage.

"Probably make more sense once I set one up and see it in action."

Yep.

 

[Iffrat]

so say you used 2 pumps .. both rated at 500gal/hr ... and one goes out .. the whole system would just run at 500gal/hr ... the overflows would auto regulate to the speed of the one pump ..

but say you had 3 at 500gal/hr .. then the overflow would not be able to keep up .. it would pull the 1200gal/hr and the returns would pull all the water it could out of the sump .. aka 1500gal/hr and the tank would overflow ..

there is not much of a reason for the sump to overflow... as long as the overflow is set up right that should never happen

 

[IrnGynt]

Got it. Thanks again!

Now I can confidently pick a pump.