Something has been bugging me.......

[chorn74]

I have heard and understand that it is better to have a built in overflow than a hang on overflow but, I cant afford a tank with a built in overflow.
which now brings us to what has been bugging me. I know that if power fails (which it does alot here in Kansas with the wind and storms) and my pump looses power and i loose siphon and then the power comes back on and im not home to catch it, Wouldnt that mean my pump would now empty the contents of my sump into my tank which would cause it to overflow all over my hardwood floor? Do they loose siphon with short or long term power outages? is there a way to stop something like this from destroying my floor?

ALL advice is welcome along with any stories or nightmares of your own.

Thanks for your time. :?

Oh -by the way I have a 58 Gal Oceanic all glass tank.
and plan on gettting a 10 or 20 gallon sump.

-John

 

[Len]

John,

It is true that if power stops with a hang-on overflow, the siphon will break and it won't start on its own after the power comes on. That means that the pump will empty the contents of the sump into the tank and possibly overflow.

There are a couple ways to combat this. One is to tee off part of your pump to feed directly into the siphon. That way, when the power comes back on, the pump will shoot water into the siphon and get it going again. This isn't always reliable and requires tinkering to get right. The second way is to use a float switch. When the water level gets too low in the sump, or when the water level gets too high in the tank, the float switch will turn off the pump. This means the pump will stay off after a power outtage. However, you'll not need to worry about flooding then.

 

[DaisyPolyp]

I had the same problem... I ended up going with a gravity-feed overflow as the only reliable method. The problem: how to you get the hole in your tank after you've already got it?

This thread worked like magic:
http://reefs.org/phpBB2/viewtopic.php?t=39570

...but it does take a stiff drink to build up the courage!

 

[MI0706]

It is true that if power stops with a hang-on overflow, the siphon will break and it won't start on its own after the power comes on.

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Well, I have a "hang on" overflow... Actually, the CPR CS-100... The only way to lose siphon between the front and the back box is for the water level in the front or the back of the box to go below the U-tube or for the U-tube to have a hole in it (even a pinhead size hole can break siphon)...

Now, since the back box is gravity fed to the sump and the water will go as low as the riser tube in the back box, if you make sure the back part of the u-tube extends downward past this point, you will not break siphon in the back box... As for the front box, physics 101 tells us that, the front box and the back box are going to equalize in water level... So, if the u-tube in the front of the box is also extended downward past this minimum water level (which is ultimately dictated by the riser tube in the back box), then siphon will not be broken...

If the above criteria are met, then the only way to break siphon in a "hang on"style overflow when the power goes out is to have the U-tube portion develope a hole... This is why most people will put two U-tubes in their boxes (just for redundancy)...

 

[candide]

Yeah, this confused me to. My hang on overflow can't lose its siphon as far as I can tell, other than me lifting the U tube out. When I go to do my water changes, I just shove the overflow box inside the tank up so high no new water enters. Then as I am draining water out with my python, I have a pump pushing the new water back into the sump (with the return pumps pushing the water back in).

As MI0706 said, it should never cause a spillover out of the tank, at least not in the way you described. Only thing I can imagine is if the back side of the overflow goes straight down...I'm pretty much a newb, but the one I have, the U goes into a 2 part chamber in the back. If it is steadily siphoning, it then spills over to the other half, which has the drain to the sump in it. If the front part of the overflow can no longer get water, the front and back halves level off, right at the divider in the back half (so no more water is being drained from the back). Hope that makes sense.

Instead, the posible leak point comes from losing power, and your sump overflowing from the nonstop siphoning. two ways to avoid this I have found...First is the easy way. Go to compusa/officedepot/staples/etc and buy a UPS battery backup. Plug just your return pumps into this. That gives you some relief from temporary outages, and time to adjust the system if it becomes a long outage.

In addition to the above, I've worked on getting a "balance" with the hang on overflow box. It is tricky, but finding the right spot to place the front box so that if the water level stays good, it flows down, but if power to the pumps goes out, the tank drains a bit to the sump, but eventually stops because it goes below the front box's intake. I couldn't do this with my sump until I added a refugium, which gave me some added water space below.

 

[silly34]

John,

It is true that if power stops with a hang-on overflow, the siphon will break and it won't start on its own after the power comes on. That means that the pump will empty the contents of the sump into the tank and possibly overflow.

My u-tube has never broke siphon when the power goes off or I cut the pumps off for maintenance. Only way to break siphon is if the tube has a hole in it or the water drops below the reach of the tube. Now you can have a snail or some foreign object clog up the tube this would slow or stop the water flow to the sump causing your tank to overflow.

B.

 

[NHMARINE]

John,
I have a Wet / Dry with a hang on over flow, I set the intake box so it's just about a half inch below below the full tank water line, if I lose power my sump can handle the amount of water above the intake box, and I don't break my syphon (the intake pipe stays full of water)
On the pump side all you have to do is install a $12 check valve in that line, this will prevent any water from back feeding into you're sump.
So when I lose power my sump fills up with an extra 4 gallons or so, my intake pipe is still full of water (because both ends are still under water) and I get no back flow from my spray bar. The power comes back on the sump returns to It's normal level, no problems. :wink:

Hope this helps you're case.

 

[hdtran]

Assuming that you have the U-tube no-lose-siphon siphon, and you have drilled a siphon break hole in your return just above (or below) the waterline of your main tank, you must still perform two checks:

(1) Simulate a power failure by unplugging all your pumps. The water in your main tank will drain into your sump via (a) siphon, and (b) siphon action of your return tubing. There must be sufficient room in your sump to accommodate this without flooding.

(2) Simulate a snail or other critter crawling into your siphon intake, thereby blocking flow from the main tank into the sump. The sump will pump itself empty into the main tank. There must be sufficient room in the display to accommodate this without flooding.

 

[DaisyPolyp]

I don't know about chorn74, but the siphon equalization method would not work for me because a simple siphon could never match the GPH flow of my return pump. So although the u-tube would be pulling water into the bakpak, the tank would overflow as it wasn't pulling fast enough. A pure gravity-feed solves this problem by emptying exactly the amount of water that the pump returns (not to mention it rids the aquarium of "surface scum" because it's intake is at surface level like a standpipe).

 

[ChrisRD]

I cant afford a tank with a built in overflow.

Another option would be to have your existing tank drilled by your LFS or a local glass shop (if you don't want to do it yourself)...

 

[DaisyPolyp]

I cant afford a tank with a built in overflow.

Another option would be to have your existing tank drilled by your LFS or a local glass shop (if you don't want to do it yourself)...

an excellent point... If you're not fully setup on the tank yet, it is definately much better to have a qualified proffesional do it.

 

[chorn74]

Thanks all for all the great info! If I decide to have it drilled how does it change the set up to the sump?
if it is drilled at the bottom of the tank how do i enclose it? with what material? Do they Have kits?
Im not sure how to do this? Do you all have any good threads or diy sites with pics?

Thanks,

-John

 

[DaisyPolyp]

If you drill it (like in the back) all you do is attach a bulkhead with seal, and plumb it to your sump. when the water pumps up to the level of the opening, it will pour down the tubing into your sump. If you drill in the bottom, then you attach a standpipe up to the top of where you want the water level to be, then when the water reaches that level it will pour down the standpipe into your sump.

If you are drilling the tank on your own, I would really only recommend drilling on the sides or back as the bottom may be tempered.

for general information regarding sumps, I highly recommend this site:
http://www.melevsreef.com/

 

[MI0706]

I don't know about chorn74, but the siphon equalization method would not work for me because a simple siphon could never match the GPH flow of my return pump.

Once again, I beg to differ... Siphon and gravity flow has no restrictions... The restrictions come with the size of the overflow boxes, the size of the u-tube, and the size of the gravity flow tube to the sump...

If you make all those big enough, you can achieve whatever flow you desire... Once again, I refer any and everyone to Physics 101 about this subject...

 

[MI0706]

Also, another way to prevent siphon back flow from the main tank to the sump during a power loss (other than using a check valve which is perfectly fine) is to drill two small holes just above the water line in your main tank on the return pipe (I chose two just in case I had that odd-ball time when a curious snail might happen to be sitting over one when the power went out)...

A way to get around a snail or debris clogging your u-tube is to use two u-tubes each one sized such that if one were to stop working, the other could carry the full load...

In all cases, redundancy is the key...

 

[chorn74]

Well my wife and I have discussed everything you all talked about and have decided to just go with the overflow box . I know having the tank drilled is better but, at this point in time we cant budget it in and im not good enough to do it myself.

I really want to Thank You all for your Great advice
it always gives me plenty to ponder about.

Thanks for your time

-John

 

[DaisyPolyp]

If you make all those big enough, you can achieve whatever flow you desire... Once again, I refer any and everyone to Physics 101 about this subject...

Okay, (walking out of Physics 101 class) so you're saying that head strength and down siphon length have noting to do with the equation? In example "A" Lets say I have 4 inches of glass above my water line, and I need to empty my siphon into a refugium 6 inches below the top of that glass. In example "B" lets say I have a bulkhead drilled into the side of the tank, and the water gravity feeds to 2 inches down to the refugium. In both examples I will use 3/4 tubing, and I have a 1,000GPH pump returning water to the tank from the refugium. The setup in the example "b" would have no trouble moving that volume of water with the water level getting near the top of the bulkhead. In example "a" I would have a wet floor as a 3/4" diameter siphon tube with a 2" drop could never pass 1,000GPH through it. There is a fluid dynamics calculation that would tell you the flow rate of a given siphon, but most hobbiests would find it easier to pop a bulkhead in the side and be done with it.

 

[hillbilly]

Most LFS's will drill your tank for $20-$30 a hole. That's a good bit cheaper than buying a overflow box.

 

[ricky1414]

Well my wife and I have discussed everything you all talked about and have decided to just go with the overflow box . I know having the tank drilled is better but, at this point in time we cant budget it in and im not good enough to do it myself.

Most LFS's will drill your tank for $20-$30 a hole. That's a good bit cheaper than buying a overflow box.

Do the drilling, much cheaper than a overflow, and easier to maintain.

 

[ChrisRD]

Personally I would have the tank drilled (or drill it myself) and DIY an internal overflow...