# Sump Theory???



## Toshogu (Apr 24, 2009)

Okay i've looked online, read some books, just want to bounce what i think I've learned before I actually put this together.










k going left to right, from the over flow water goes in goes through stuff, dumps into that middle spot, overflows that last barrier on the right, shoots back up to tank via pump.

Now... if I understand this correctly if the pump in the sump fails the water will continue to go into the sump untill the water lvl reaches below the overflow box's lvl and the water from the pump will flow back in. so if you stick the overflow just about where you normally keep water and run a rain bar one the pump outflow the sump shouldn't overflow i.e. get water on your floor.

Now... if the overflow box stops sucking water (airbubbles, water goes below level) and the pump keeps going, what's to keep your main tank from flooding?

what if I were to make the 2nd to last, and last wall about an inch lower than the first wall, and stuck the powerhead so the intake is only about 2 inches from the top of last partitions water lvl? would that prevent main tank flood if overflow box stops working but powerhead still pumps?

what are the disadvantages of sticking powerhead so high vs sitting on the bottom of last partition?

is this solid sump theory or am I off base?


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## Toshogu (Apr 24, 2009)

K, got something more simple. only thing is that the pump that I bought seems to put out alot of heat. Mag-Drive 250, is there a better alternative?


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## jones57742 (Sep 8, 2007)

Ts: IMHO wet/dry's are not worth the pain for tank sizes less than 100G.



Toshogu said:


> Now... if I understand this correctly if the pump in the sump fails the water will continue to go into the sump untill the water lvl reaches below the overflow box's lvl and the water from the pump will flow back in. so if you stick the overflow just about where you normally keep water and run a rain bar one the pump outflow the sump shouldn't overflow i.e. get water on your floor.


Ts: Correct.

Instead of a "rain bar" you might consider like four submerged discharge orifices in order to allow you generate beneficial currents in your tank.

You will need a back-flow preventer in the pump return to the tank tubing.




Toshogu said:


> Now... if the overflow box stops sucking water (airbubbles, water goes below level) and the pump keeps going, what's to keep your main tank from flooding?


*Nothing!* but if you do not have a drilled tank that is reason that you do not skimp on the tank to sump return fixture.

You will want a dual box fixture.

One box is on the inside of the tank and the other is on the outside of the tank and they are connected via a "self restarting" siphon.

The inside box should have a fairly linear weir overflow instead of holes or slots as with this type overflow the water will continue rising until the water surface is above any overflow impedance.




Toshogu said:


> what if I were to make the 2nd to last, and last wall about an inch lower than the first wall, and stuck the powerhead so the intake is only about 2 inches from the top of last partitions water lvl? would that prevent main tank flood if overflow box stops working but powerhead still pumps?
> 
> what are the disadvantages of sticking powerhead so high vs sitting on the bottom of last partition?
> 
> is this solid sump theory or am I off base?


Ts: Your theory is OK but you are off in your terminology and IMHO you may be off in your implementation.

A Mag-Drive 250 is not a power head but a pump (the significant difference is in the head/discharge curve).

The wet/dry IMHO should have a minimum turnover rate of 4X and for a 100G tank your Mag-Drive 250 will be much less than 2X.

I prefer an *external pump* due to efficiency issues which relate to heat issue which you entertained in your 2nd post.

The gross sump volume, IMHO, should be a minimum of 33% of the tank volume.

The operating water surface in the sump should be established such that should the pump fail the sump will contain the water between the typical water surface in the tank and the bottom of the overflow weir (or else you will have a puddle on the floor).

The top of the underflow plates should be an inch or so below the top of the sump in order to implement a safety bypass (or else if a chamber clogs you will have a puddle on the floor as well as a crispy critter pump).

This comment is based upon my experience with a poorly designed prefabricated wet/dry which came with my money pit: IMHO the volume of the mechanical filtration media chamber should be 1/4 of the total sump volume; the volume of the biological filtration media chamber should be 1/4 of the total sump volume; and the volume of the reservoir chamber should be 1/2 of the total sump volume. Please note that you can place media bags with biological filtration media in the reservoir chamber should you want to.

TR


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