Continuous water swap?

[underdog5004]

So, I have a tank with plants in it which need nitrates, and a tank full of koi right next to it. Is it feasible to have a water pump in each tank, pumping water into the other? That way, the plants are fed, and the fishwater is kept clean.

Ideas, suggestions?

 

[mgamer20o0]

i often see it as a sump type set up. big tank with smaller one under with light and plants. its possible. great idea of solving problems.

 

[asudavew]

It would be quite difficult.
The pumps would have to pump at the exact same rate.
Or one would over flow and the other would empty.

The sump idea, that mgamer2000 suggested, would work though.

 

[neilanh]

It is a workable concept, but like said above, it'd be near impossible to use pumps in both directions effectively. This is because the different conditions for each pump would cause them to never pump the same amount of water equally, and eventually you'd overflow one of the tanks.

What you need to do is use a pump in one direction and a gravity feed in the other, exactly the same way a sump system works on a SW tank.

 

[underdog5004]

Wouldn't the gravity feed still have the potential to overflow the tank?

What if the pumps were locate near the surface of each tank? that way if one started to get too high, the other one would stop pumping?
I think I'm going to try it out soon with the tanks half-full and see how that goes.

 

[neilanh]

as long as the gravity feed is shaped so that it can handle more water than what you're pumping, unless it gets clogged you'll be fine.

If you place the pumps at the surface in order to use that as your safety measure, you wouldn't be able to maintain the tanks fully filled to allow room for things to go bad. Additionally, when the tank with less flow drops the water level below the pump, you'll likely burn up your pump.

 

[timwag2001]

how about if you could somehow make your plant tank air tight. you could use one pump and the plant tank could never over fill.

 

[jsoong]

If you seal off the planted tank, how would you clean & maintain it?

The only safe way to do what you are proposing is to set it up properly as in a sump. You will pump water from tank A to B, but have the water return by gravity. <Using 2 pumps is a recipe for disaster ... any little thing happen with one pump to alter the flow rate & you will have a flood .... >

Since the tanks are at the same level, the return will have to be a siphon connection. <Drilling the 2 tanks will be even safer, but I presume that is not an option.> Any sump setup will need to have some room at the top of both tanks in case of pump or siphon failure. Also, if the tanks are of different height, you'll need to leave even bigger headroom (as the siphon will make the water level the same in both tanks ... so the taller tank will have a lot of wasted space.)

In summary, it is doable to connect 2 tanks, but it takes careful planning & execution.

This is a couple of example of it in use:
http://www.seanbuckley.ca/blog/2007/01/09/the-fish-highway-rat-tubes-for-an-aquarium/
http://ellerg.blogspot.com/2008/08/fish-highway.html

 

[timwag2001]

i said somehow. didnt say it was possible

 

[underdog5004]

I've been doing a lot of thinking, and I think the easiest way to do it is to drill the tanks. Unfortunately, it's not possible at the moment.

Just so I'm clear on the concept of the siphon method, I'm going to start a siphon from one tank to the other, both of which are on level, even ground, and level with each other, and then pump water from the other tank back to the original tank. Does that sound right? I really want to make sure I get this concept down BEFORE I do any flooding

Thank you all for your input, it is much appreciated.
Oh, also, just got a 29 gallon kit!

matthew

 

[jsoong]

You got the basic idea. To refine the concept some more:

1. The siphon must be large enough to handle any flow your pump put out. The 2 ends of the siphons also should be deep in the tank so you don't lose siphon with a drop in water level. (evaporation, pwc ...)

2. You should set the pump up so it will only take water from the top of the tank. <eg. use an external pump & set the inlet just 1" or so under the water level.> This way, if the siphon fails, you can only pump so much water before the pump runs dry. You should have room in the other tank to contain all the water the pump can pump without a siphon. <ie the starting water level needs to be lower.>

3. you can add safety switches to cut off the pump when the water reaches a certain level in the "receiving" tank. <Not absolutely needed if you set your primary safety by the pump level, but redundancy is good.> Also, it would be a good idea to get a pump with an auto cutoff if it runs dry. <If the siphon quits & your pump runs dry for a long time, it will burn out the motor.>

 

[underdog5004]

so, here's an update:

I put a small water pump in the 20G planted tank to pump clean(er) water into the koi/carp tank (55G). From the koi tank, I've got 2 airline size hoses siphoning water back into the plant tank at a rate slightly lower than the pump rate, so the water level in the plant tank would keep dropping, if I didn't have the pump pretty high in the tank. The pump doesn't seem to be overheating, and the water level seems to be pretty constant. Ideas? Comments?

Matthew

 

[fort384]

is the pump ever running dry?

 

[jsoong]

The siphons are supposed to have a capacity GREATER than the pump ... the siphons will only move water as fast as the pump & not more, the extra capacity ensures you don't have floods/dry pump.

You are currently pumping more water out of the planted tank than the siphons can return, that's why the level is dropping. You are preventing flooding by placing the pumps up high, but I suspect that they are running dry. <The unequal water levels also will drive more water through the siphon, but that is a bit risky .... signs of adequate siphon size is equal water level in the 2 tanks.>

I think you should go at least 3/8" (ID) with your siphon, airlines clogs much too easily for my comfort. <For reference, a 1" siphon will handle ~600 gph. Flow rate varies with the 4th power of the radius if you are trying to calculate the min. size ... but most people just oversize the thing & be done with it.>

 

[krap101]

Yeah, I was reading through this thing and a sump/overflow seemed like it is exactly what you are looking for. As jsoong pointed out, the overflow would have more capacity than the pump, because as the water level drops, less water would go back into the sump, and it would have a nice little equilibrium. To stop the sump from flooding, most people put some sort of break so if the water level goes under a certain point, air will get in and stop the siphon. (power outage) I hear that it is obnoxious to start back up though.