Siphon VS. Pump

i thought mag pumps actually are more efficient if there is some back pressure? i heard that somewhere.

 

I'm referring to the piping or hose that will be draining into the sump from the aquarium/overflow. If the hose is submerged, the flow coming out of the aquarium is controlled by the amount of water leaving the sump (pumped back into the aquarium). If you have the overflow just dumping from mid air into the sump, it's releasing at it's own rate, rather than by the pump. Does this make sense?

It seems to me that the water exiting the aquarium should be submerged in the sump to insure and manage rate of flow and overflowing the sump. If the overflow, pump and output are all submerged; once the sump is filled and the pump is turned on, the water begins to cycle?

 

What is labeled on the boxes is max head. That is totally different from head loss. Max head is an unrestricted flow in a vertical straight line push. Head loss is deductions of the restriction caused by pipe diameter, fittings and valves. Every one of them add to your head loss and deducts from your max head.
I totally agree with Jwin. Never put a valve on the line to control flow. Also use the biggest possible tubing for your return. Mag drive pumps (and I'm not talking just Danner but all) aren't built to handle back pressure. It makes them work harder. They get hot and that heat transfers to your water.
An over rated pump is by all means ok to use and in some instances necessary to achieve the desired flow. I have a 300gph overflow and use a QuietOne 4000 which is rated at 1250gph at 0 head.

 

Oh no. Don't even consider using a tube with a siphon straight from your aquarium to your sump - that's asking for serious trouble.

You want something like this:

...which is a pair of boxes, with one box in the aquarium, and the other on the outside of the aquarium.

A straight siphon won't allow you to manage the rate like an overflow box will. It will go at its own pace, regardless as to the return pump's rate. This design I have, however, will allow for your overflow box to match the return pump at any speed up to the max capacity of the box.

 

Haha. Yes, that's what I meant. Using an overflow box, but wouldn't the box run at it's max rating? I.E. 500gph. If that is the case and the overflow "dumps" directly into the sump, and you're running a 250gph pump, that should overflow? Or is there someway on the overflow to manage the rate of flow? The only way I see this possible is that the overflow hose is submersed in the sump.

 

No, the pump controls everything. I have my drain end under water. It helps with salt creep as you don't get splashes. The U tube or overflow will only drain what is being pumped back into the tank. The box that goes inside the tank that has teeth sets the water height in your aquarium. I don't know the physics or mechanics behind it exactly, but the simple answer is that it doesn't matter. the return pump determines how much water goes back into the tank and how much is drained from the tank. (This of course is using a HOB overflow box with prefilter box inside the tank).

 

+1 to this. No more can be drained out of the tank than what is pumped into it for the reasons Guitarman89 stated.

 

Agreed. its kinda hard to explain but lets say your hob overflow can handle 500gph and your pump is only 250 gph. your overflow will only be draining at 250gph. regardless of how the line going into the sump is(in the water or above the water) it will only drain as much water as you are pumping into the tank.

 

You can put an Inline valve with your return pump, the higher it is the safer for the pump it. Check out the thread "quickie plumbing question" for more details on it. If you didnt want to take the chance of damaging the pump you can tee off the return. Have one go to the tank and the other go back into your sump. The plumbing that goes into the sump would be where you put your valve. This worked for my old tank. BTW dont use a ball valve, use a gate valve easier to control.

 

I was going to mention the tee but decided against it from past xp. But it's actually the best method for using a valve to control flow w/o putting any back pressure on the pump. I agree with the gate valve statement only to the point that control is more definate but on the other hand there's way more to go wrong with them and the o rings wear out pretty fast. If a ball starts to stick I just take it off line and soak it in vinegar for a while.