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Old 10-09-2008, 06:43 PM   #41
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Yes! Too powerful!
I think that point has drifted aside while I worked on other things. Back to it: whether or not I can return the magdrive24 (waiting to hear back from merchant) or recoup some of its value on craigslist I will need a less powerful pump. For the brand: I am willing to pay more for silence, though I don't know if I have 2x more flow than I need or just a couple hundred gph to lose...
A post in hardware hasn't yeilded any advice on make/model...

Siphoning from the bottom is just one of the funtions of the U pipe, the other is to get the water moving back into the sump because of the 2 inches (10 gallons) of rise in the display tank needed to get to the OF box so the sump doesnt run dry.

Adding a second U helped a little, so I am building a 3rd and 4th right now... pics in 30 min or so...
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Old 10-09-2008, 08:24 PM   #42
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Your baffles looked fine to me too. On the pic, it almost looked like there wasn't a gap at the bottom of your "return/filtration" compartment causing all that water to spill over the 1st baffle. Well, all the water going over top of that compartment would indicate that your pump flow is too much for your sump! You are going to have to use a smaller pump or set up that diverting T you had before. <BTW - if you can set up the diversion easily, it would be a good way to find out how much flow your system can handle before going out to buy another pump.>

As for the overflow on top, you can't have water spilling over the top since that would have too high an operating water level in your tank. At your first test, your pump was drawing air because you can't keep enough water in the sump at your current overflow level. My suggestion was to lower the operating water level so you don't drain down as much water into the sump at power off, allowing you to keep the sump fuller. If you want to take water from the top as well, you will need to make a skimmer box at the lower water level & connect that with a siphon. I am not sure if that is worthwhile doing. Your problem is the overflow box being too high compared to your platform, it might be simpler to re-do the overflow box & dispense with all the siphons....

But since you are already making more siphons, you may as well try that & see what happens.
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Old 10-09-2008, 09:25 PM   #43
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took longer than 30 minutes

I will start the system at 9, giving the glued parts more time to dry...
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Old 10-09-2008, 10:42 PM   #44
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OK, ready to go, everything set except pump running.

Here are photos of water levels when pump is off:
(BTW, getting both durso pipes to exactly the same level as minimum display was tricky, but testing without the U siphons shows that the 2 levels are equal)










I do not intend for the water to not spill over the OF, the U siphons are meant to pull from the bottom of the display and help to ease the transition...
Let's see what happens................
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Old 10-10-2008, 11:43 AM   #45
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How is it running with the modifications?
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Old 10-10-2008, 05:16 PM   #46
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Internet went out last night before I could post...

The same basic problems occur, but slower...

The pump eventually runs dry, but it takes much longer than before.





The water runs over (instead of under) the first baffle, but it takes longer to happen and not as much as before.





The water goes over the overflow, and the IN flow is more than the 1" and 1.5" durso pipes can send back out. Since the pump can run longer before it runs dry, it continues to raise the display level, it got about 2" above the OF before it ran dry











So...
-If the durso pipes are at full siphon, how much flow is leaving the tank?
-This would be my maximum return flow?

The 2400 is too powerful, and noisy, I will replace it with a brand as close to silent as possible, what would you estimate the gph to be?
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Old 10-10-2008, 08:10 PM   #47
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I think it would be worthwhile to consider the parts seperately to get an idea of what each can handle. I will give you a theoretical approach for the estimating, hopefully saving you a bunch of experimentation.

I would use the laminar flow equation to estimate what flow you will get. <I know the flow won't be all laminar, but the turbulent equations are too hard to use, and we are estimating anyway!> This is the equation:

Flow = (Pi x r^4)/(8 x n x l) x dP

r = radius of your pipe, l = total length of pipe, n = viscosity of water (constant), dP is the driving pressure - or how high your water level is to drive the given flow.

Instead of trying to figure things out by plugging in the values directly, I would suggest taking an observation & using the equation as a proportion. This would account somewhat for the elbows, constrictions, & other imperfections in your piping that causes turbulence.

Since the Dursos appears to be the bottleneck, we will consider that first.

You need to measure what driving pressure is needed to handle your pump flow. To do that, you need to add more water to the sump so your pump won't run dry, and measure how high the water is in your tank once you get everything balanced. dP is the distance from the top of the water to the inlet. < Yes, you will have more water than is safe .... so make sure you do this outside if possible .... or be ready to plug both standpipes before you turn off the pump & drain out excess water in the tank. >

Once you know that height (we know that it is at least 2" above your overflow top), you can figure out what flow the system can handle at your planned water levels, like this:

Since r, n & l are unchanged, you can simpify the equation to:
Flow = dP/R ...... R = resisitance of the setup.

Using 2 sets of equations for the 2 flow conditions, combining the 2 equations ....

Flow1 / Flow2 = dP1 / dP2

Say Flow1 is your Mag 24 at 2000gph, and your driving pressure dP1 is 4", and you have only enough height in the setup to give a driving pressure of 1" (dP2) ....

Plugging everything in gives you a Flow2 of 500gph .... this is what gph your setup can handle. <I would not run a pump right at the edge of system capability .... cut back 25-50% to handle the invariable glitches during operation.>

Of course, I am only guessing at the numbers by looking at the pics. Try with real measurements & see what you get. The Dursos should be able to handle more than 500 gph, even at 1" of head height .... so you might be able to tune the system for better performance <eg - changing the air hole size>. If you can't get the Dursos to handle an acceptable flow rate, you'll have to consider using an open channel design <in an open channel or full siphon setup, dP is the height between your overflow & your sump .... so can handle much higher flows>, or re-designing the overflow. The other option - dropping the height of the Dursos to gain more head height is not safe with the siphons taking water from the bottom - since the minimum water level would be too low & you'll flood the sump with a power out.
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Old 10-11-2008, 10:25 AM   #48
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One other thought came to me overnight ....

Your pump is in a small compartment, giving you very little water to work with. For testing, why not move the pump into the main "fuge" compartment. This might allow you to run the system & get your levels without the pump going dry.

In real operation, you would want the pump in the last compartment as those baffles acts as air & dirt trap to reduce clogging of the pump (& bubbles in tank).
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Old 10-11-2008, 10:37 AM   #49
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I am installing a ball valve in the return line to get a rough idea of how many gph I want in a new pump, thanks for the formulas, that will help to confirm my finding or maybe narrow it down further.

The problem with the open pipe is that the water level fluctuates between a full siphon and a gurgling drain until water builds back up to create a siphon which drops it again bringing air into the pipe...

Though if it offers much more flow maybe I should have 1 open and 1 durso?

--->The hole in the top of the durso, I thought this was to vent air as the water levels moved, would a larger hole lead to faster flow?


...I will see if there is enough room to move the pump to the fuge compartment as well
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Old 10-12-2008, 10:38 AM   #50
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I can't move the pump's position within the sump but...

With ball valve half closed the systems runs!

The display level gets to 1/4 inch above the OF...
The teeth I am adding are about 1/2 inch tall so there should be enough flow through the U siphons with some good skimming of the surface...
The durso pipes, they don't flow much with the holes open, so after plugging the big one with the tip of my finger and seeing the OF level instantly drop I realize my holes are too big...
Little bit of masking tape and a pin to slowly widen a hole in it led to a alternation between full siphon and a slow fill up of the OF box, full siphon and then slow fill...
I am sure a balance needs to be found but I am happy to just see things finally doing what they should.

Water is still coming over the first baffle, I think the only solution is to add height to it? Silicone sealant and some plexiglass? Silicone sealant is also how I am gluing the teeth on?

GPH... Hard to get more detailed than 'ball valve half full'
I can't really adjust anything once it is running, or make any slight adjustments for that matter, I can only be pretty sure that it is closed exactly halfway...

So, I plan for a gph that is slightly overpowered, and get the T off valve set up again to fine tune the flow.
Do you think it should be more like 1200 or 1600?
Do you have any advice on tweaking the dursos?
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