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Does this overflow/sump design make sense?


chippwalters

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Hi All. I have a question about a combo overflow sump design. It's a bit different than most, as the sump is the exact same tank as the display and is designed to be on the same level, and will be using a siphon type overflow. And, yes, I know it's better/safer to drill through the back, but the display small tank is already in use and all I want is to almost double the amount of water for it while making it much easier to maintain.

 

First, here's the schematic. It's more diagrammatic than an actual design, as I can make things fit better as I build it.

 

Photo%20Dec%2018,%204%2051%2034%20AM.jpg

 

So, as you can see, I've basically done away with a full overflow design. My thinking is there's no risk of overflow of the sump because both tanks are level so if the pump quits there's no risk of the sump flooding. And on the other hand, if the siphon quits, there's not a lot of water which can be pumped back into the tank (as shown by the blue hatching in the diagram).

 

Does this seem like a good design? I will also have a second powerhead in the display tank to help with the current and flow demands. Any and all comments, critiques and suggestions are welcome.

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I'd remove the "vent" and put the return control valve in-line just after the pump. Placing the return nozzle close to the surface should prevent too much backflow into the sump area. Even if it dosn't, the sump tank would not overflow. Skip the Bio pellets and use mor LR if it seems necessary. You may be able to remove one or two baffles as well (Sucks to try and glue those things in). Chemiclean may reduce flow and the sponge may be difficult to get into for maintence.

 

That was pretty harsh... Sorry

 

-pinner

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You may have microbubble problems, as any air sucked out of your overflow will be sprayed directly into your display. It shouldnt be too much of a problem normally but if the power goes out you might have serious problems. You would have to make sure that if the power goes out, there will be enough water in the section with the pump that it will not run dry. When the pump restarts, it will take about 30 seconds to prime the overflow. In this time your pump will suck all of the water out in that section and run dry, shutting down the whole system

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I'd remove the "vent" and put the return control valve in-line just after the pump. Placing the return nozzle close to the surface should prevent too much backflow into the sump area. Even if it dosn't, the sump tank would not overflow. Skip the Bio pellets and use mor LR if it seems necessary. You may be able to remove one or two baffles as well (Sucks to try and glue those things in). Chemiclean may reduce flow and the sponge may be difficult to get into for maintence.

 

That was pretty harsh... Sorry

 

-pinner

Harsh? No way. Harsh would be taking the time to build this and it doesn't work. :D

 

The reason for the return flow valve in the position it's in is to create less stress on the pump motor. I read somewhere doing it this way saves adds to the pump life as this design does not restrict the flow output, only the output to the display tank.

 

When you say "Placing the return nozzle close to the surface should prevent backflow" are you talking about the close to the surface of the display tank? If so, then the idea it would backflow only until the water level in the display tank dropped below the return nozzle, right? That sounds smart.

 

Yes, now that you mention it, the bio pellets do seem redundant. And.. I was wondering about if there was enough flow to push the water through the charcoal. How do folks keep the water scrubbed in one of these? More surface area to the carbon filter?

 

I was under the impression the baffles killed the microbubble problem-- is this not so?

 

You may have microbubble problems, as any air sucked out of your overflow will be sprayed directly into your display. It shouldnt be too much of a problem normally but if the power goes out you might have serious problems. You would have to make sure that if the power goes out, there will be enough water in the section with the pump that it will not run dry. When the pump restarts, it will take about 30 seconds to prime the overflow. In this time your pump will suck all of the water out in that section and run dry, shutting down the whole system

 

Thanks for taking the time to respond. How dangerous are microbubbles? Isn't the baffling at the end of the sump designed to remove microbubbles?

 

Here's how I see the power out scenario: If the power goes out, the water level in both tanks becomes even-- driven by the siphon. Then when it comes back on, the pump starts and begins moving the water from the pump chamber into the tank. I don't see where there needs to be a prime for the overflow-- or am I missing something? It seems like the overflow stays primed during a power outage as the siphon should be fine. The vacuum from the venturi to siphon is a fail safe to make sure there is no problems with the siphon over time-- but technically not necessary 100% of the time.

 

But, if there WERE a siphon leak, then I suspect when the venturi quits, the siphon COULD stop, leading to the scenario you describe.

 

Now, on the otherhand, if the siphon ever malfunctions, then certainly your point is paramount. But, I just don't know much about microbubbles and what effect they have on a tank. I'll see what I can dig up.

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thadscottmoore

I would lose the vent too. makes sense about the back pressure valve- that is how I did mine on my RSM tank/sump. return just below water level in the display- break siphon in event of power failure-

 

 

 

how big is the sump going to be? it would be difficult to incorporate baffles into such a tight space. though, I dont think microbubbles would be an issue really.

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Last baffle is unneeded and the last compartment will be where your evaporation will show. There is no reason to have the water level that low in the last compartment as the splashes will increase evaporation. Make it at lease 2/3 the way and just vacuum it with some airline hosing during water changes or once a month to get the crud that might settle at the bottom.

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If you put a vent there... won't the pump just pump water out of the vent?

 

If you put the return flow control output above the water line in the sump, that will prevent backsiphon (provided that it's high enough in the sump).

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I would lose the vent too. makes sense about the back pressure valve- that is how I did mine on my RSM tank/sump. return just below water level in the display- break siphon in event of power failure-

 

how big is the sump going to be? it would be difficult to incorporate baffles into such a tight space. though, I dont think microbubbles would be an issue really.

 

I suppose the back pressure valve, if left open would also act as a reverse siphon. In any case, even if it did siphon back into the sump, it wouldn't cause any more of a problem than if the pump quit.

 

 

Last baffle is unneeded and the last compartment will be where your evaporation will show. There is no reason to have the water level that low in the last compartment as the splashes will increase evaporation. Make it at lease 2/3 the way and just vacuum it with some airline hosing during water changes or once a month to get the crud that might settle at the bottom.

 

Thanks for that. Good points!

 

If you put a vent there... won't the pump just pump water out of the vent?

 

If you put the return flow control output above the water line in the sump, that will prevent backsiphon (provided that it's high enough in the sump).

 

See first comment. Working with everything on the same level makes some of this simpler, but one thing less simple, as I was reminded by my LFS guy-- that is the siphon suction is considerably less, and more prone to failure. I need to keep thinking...

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what program are you using to draw that? it looks too neat to be drawn by hand but not neat enough to be a cad drawing.

 

I'm using Neu.Notes+ on my iPad along with a stylus like this one. I've tested all the sketch and note apps and find Neu.Notes+ has the features I want. I also used it to sketch the drawings at:

http://www.nano-reef.com/forums/index.php?...t&p=3507314

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