sump driving me crazy over flow

[zaireguy]

Hi All

I can not get my sump to stay at a certain level.It either over flows or emptys on me.I have a mag 7 going into the sump and a mag 7 return water into main tank.I have flow controls on both tubes.But the water lever will not stay the same.

I unhooked the sump for now till I get this straight.I have micro and some nice worms and bugs going in my ref.I stuck a air line in there to supply air for now.Any one know a sure fire way to get this adjust out right.My ref sets on the floor it is 30 gallons.

If not do I do weekly water changes in my ref to keep my critters going.Any help would be great I have tried everything.And my wife will not stand for a nother over flow
thanks
Ron

[aquaticsdeptleader]

the mag seven return will not match the mag seven input do to length that the water travels i believe the technichal term is head pressure? essential the gallon per hours slow down the farther the pump needs to push the water. I would get an over flow box

you may have the emtying effect because you over compensate the flow control on the input pump.

if you really want to do it this way find out the gallon per hour the mag pumps at for the height it needs to pump then adjust input mag accordingly (think this may take alot of tweeking and any shut off might throw way out of wack)

if iam wrong someone correct me

[Frank]

You are correct you have to have an over flow box. I had tried it and you can not match the pumps. End the end one will over flow or empty. Hope this helps.

[Etech]

Try teeing off your return to your tank and feed it back to your sump with a gate valve . that way you can control your flow back to your tank .

[UnseenTric]

Ahh... this problem drove me absolutely nuts when I first started my tank. The answer, believe it or not, is found in calculus. Your 2 pumps are working in series and thus generating an "Unstable Equilibrium curve". If you analyze the slope field of such a curve you'll see that it is IMPOSSIBLE to Match these flows even with tweaking (via needle valves), I promise you.

Here's the mathematical explaination...
Think of the flow to and from the sump as constant (parallel to the X axis). Your y-axis is flow of water, and your x-axis is time. What an unstable equilibrium dictates is that as soon as the flows from the tank to the sump and to tank from the sump become unequal the Sump will empty (if the flow to the tank is greater) or Overflow (if the flow to the sump is greater). The Curve moves away from the equilibrium constant expontentially! This will enevitably happen no matter what you do. For example a tiny piece of algea will momentarily slow the rate of one of your flows.
This is best described by a graph, if any one really cares I can draw and post what this graph looks like.

What was suggested above was to install an overflow box, this will fix your problem by setting up a "like" stable equilibrium curve.
If you really care to know the math behind why the overflow box works I will post why, but somehow I have a feeling that no one really cares. Nevertheless, even though I fought with it for 3-4 days before resorting to my calculus textbook I found it to be one of the more enlighting situations about how my water movement works.
Good luck with the new tank!

If you want to see any of the Equilibrium curves tell me, and I will try to draw them (on the computer) and post the image.

Pete

[hamburglar]

It seems as though some of you may have missed part of zaireguy's question.

He said that he has a 30 gallon reef tank sitting on the floor.

I would suspect that your sump is also on the floor?
What size is this sump?

If the tanks are equal height, you can simply use a siphon tube to return water from your reef tank to the sump tank. However, this tube will have to be quite a bit larger than your line on the pump to move the same amount of water.

You may want to set your reef tank up on a raised stand, with your sump positioned below the reef tank. Then, you can use some sort of overflow device, to return water to your sump. All the water that you pump into the reef tank should return into the sump in the same volume as it "overflows" back into the sump.

[platapus]

This mught be redundent

lol -

UnseenTric is absolutly right...using 2 of the same pump will never work!

If you use one pump, and a siphone tube that hamburglar suggest, keep the tanks the floor, they will both always have the same water level, as water evaporates.

Drill your 30 gallon, or purchase a overflow box:
http://marinedepot.com/a_of.asp?CartId=

[davesy]

sir i have tried battling the situation before i end up askin my friend to build me another tank and drill two 1 1/2 whole in it. very disappointing when you think it is fine and in a minute the other pump starts to pump faster then you will have to adjust again. my suggestion, it is easier to regulate just one valve, choose where you want to put it intake or the outflow let the other pipe be in constant rate. can i ask in relation to this, how can i eliminate the bubble that the intake of the main tank have? i have tried submerging it but bubbles still exist.
just my opinion

[zaireguy]

thanks for all the info a over flow will be installed this week end.