# Power outage safeguards for siphon overflows.



## One_Cich_Dude (Feb 2, 2009)

I am going to the local walmart tomorrow to buy a 55 gallon tank and stand, and the local hardware store for PVC, egg crate, and all kinds of things.

I have spent the last week researching siphon overflows and had come to the conclusion that there simply is no 100% safeguard in the event of a power outage, other than buying a powerhead with a venturi to suck air from the top of the siphon tubes.

However, I think I may have come up with a solution that just might work.

What if you took a regular HOB filter, and drilled the bottom of it's box for a bulkhead, then used a regular siphon tube going into the HOB filter?

The filter's power suction tube is self-priming, as long as there is water in the filter box. All one would need to do is put the overflow tube in the filter box high enough to leave enough water in the box for it to self prime in the event of a power outage.

Of course, one would need to buy an HOB filter with a sufficient GPH rate to keep up with the return rate, and drill the HOB's intake tube for a siphon break (or shorten the tube) high enough to prevent losing half your display tank's volume into the sump and floor.

But, I think this method will provide the most reliable self-priming overflow foor those who can't or don't wish to drill their tanks.

There is a local glazier in town that I will try to have drill my tank for an emergency overflow (a single 1" bulkhead just below the rim of the tank) to prevent a catastrophy in the event I lose siphon and the return pump kicks on.

But, if this turns out to be too difficult or too costly, I am going to try using an HOB filter as a "self priming overflow".

Has anyone else tried this, and do you think it will work?

I'm looking for critique so I don't buy a bunch of unneeded pipe and fittings in case it's a fool's errand.


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## KaiserSousay (Nov 2, 2008)

Yo Dude..I think if you looked closer at the various pvc overflows in this fourm(and many others) you would see that all of them shut themseves off, at a tank level chosen by the builder, by a siphion break. With PROPER construcion these systems will restart themselves as the water from the sump returns to the tank.
My "pretzel" would always stop and start at a level selected by me to suit my sumps capacity.
The main problem with these systems is the noise..that said..what noise is to one, is hardly noticable to another.


> HOB filter with a sufficient GPH


That is going to be your biggest problem, one of the advantages of a sump is the large volume of water moved thru it.
Not saying it`s a bad idea..I just think you might be starting down a path which will take you back to where you started, with a bit less $$$ in your pocket.
Whatever you decide, Good luk to ya.


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## One_Cich_Dude (Feb 2, 2009)

KaiserSousay said:


> Yo Dude..I think if you looked closer at the various pvc overflows in this fourm(and many others) you would see that all of them shut themseves off, at a tank level chosen by the builder, by a siphion break. With PROPER construcion these systems will restart themselves as the water from the sump returns to the tank.
> My "pretzel" would always stop and start at a level selected by me to suit my sumps capacity.
> The main problem with these systems is the noise..that said..what noise is to one, is hardly noticable to another.
> 
> ...


 

I understand the "self starting" nature of the DIY siphon tubes. But they also require finicky check valves, and can lose prime if gasses are introduced by microbes growing inside them. I have read that the easiest solution to counter the gas buildup and subsequent loss of prime is to attach an air line from the siphon tube to the venturi inlet on a powerhead.

But, an HOB filter will self prime even if it's siphon is completely broken, as long as there is water in the filter box.

I think adding a drain pipe to the filter box of a large HOB filter to supplement the existing DIY siphon overflow would help reduce the risk of a flood should your DIY overflow lose it's prime for some reason. The HOB filters are self priming, even if their siphon is broken.

I have read on MFK forums huge 70+ page thread about the DIY siphon overflows that they were considering placing the air line from the top of the siphon in the return line and seeing if a venturi effect would self prime the siphon tube without running the line to a powerhead. Unfortunately, nobody there actually tried it. I suppose I could experiment with it and see if that method would work, thereby eliminating the need for the HOB filter.

But, I never studied fluid dynamics and don't know how to fabricate a venturi.


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## KaiserSousay (Nov 2, 2008)

> never studied fluid dynamics


Me neither, other than out of a bottle or can  
Take a look at Aqualifter pumps..They have the features you might be looking for, at a real do-able price.
Keep us informed on your progress...please


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## mithesaint (Oct 31, 2006)

Interesting thoughts.

If you're planning on having the tank drilled anyway, why not just use the holes for the overflow and not mess around with the siphons? I thought the point of a DIY overflow was for those of us that didn't want to risk drilling a tank...

My DIY overflows work great, never had a problem, FWIW. I doubled up so that if one loses siphon, the other can handle the flow. If they both lose siphon, and I don't notice...Uh oh. So, if you're concerned about losing siphon, add a second overflow. Cheap and easy. My two overflows are well hidden by large pieces of driftwood.


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## mithesaint (Oct 31, 2006)

Forgot to mention...the last power outage we had, my overflows restarted perfectly. My HOB on the other hand, didn't. Had to restart that myself.


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## One_Cich_Dude (Feb 2, 2009)

Well, I built one of the common overflows today using 3/4" pvc. My pump easily outperforms it.

The one I built is the kind that draws water from the bottom of the tank and relies on athe tee fitting to break siphon. Unfortunately, using 3/4" tubing with the tee high enough not to flood the sump filter, I don't get enough flow. I am going to try a different configuration tomorrow using my remaining 3/4" fittings.

If I can't get a satisfactory flow rate, I'll change over to 1" pvc.

(I forgot to mention, I decided against drilling the tank.)

I will look into one of those aqualifter pumps.

I tried to make a venturi by drilling a hole in my return line and inserting the air hose from the check valve. It worked, but it was only strong enough to lift water 4" up the air line with the opposite end in the tank water. I'll have to keep experimenting with it until I can get a good suction going. This wouls eliminate the need for a powerhead or an aqualifter.


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## KaiserSousay (Nov 2, 2008)

Flow rates and noise on a pvc overflow seem to be the bug in these cheap to make units.
If someone could come up with a way for these to safely start and stop, on full siphion, both problems would be gone.
My 3/4 "pretzel"would flow like gangbusters, no noise at full siphion. That is what got me looking at the aqualifter, as "power outage" protection for a full siphion overflow.
Well, not just outages, trying to do a simple water change became more than a headache. 
Sure, you could throw alot of money into solenoid valves,float switches, and vacum pumps to safely start and stop your overflow, but when you were through, you have spent more than a quality canister would cost you.
BTW..just occured to me..that would have to be a "killer" hob to pull enough water into it`s filter chamber to supply water for a sump.


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## One_Cich_Dude (Feb 2, 2009)

The HOB I have now (that came with the tank) is one of those dual filter jobs with an intake of about 3/4". It's pretty strong, and primes itself, but I think I'm going to abandon the idea and work on making a venturi for the return line to prime the overflow siphon.

Here are some pics of the progress on the tank so far...

Here's some detail of the filter box construction.










I used the lock ring from a 3/4" pvc electrical conduit bulkhead fitting.










The wet/dry filter is constructed of these small stackable storage containers I found at walmart. They separate to allow for changing media in each chamber individually.










The sump. Approximately 15 gallons. It was the biggest one I could find that actually would fit in my stand. The pump has had a 3/4" pvc check valve added to it to prevent return line siphoning in the event of a power failure.










Here are a couple images of the first iteration of my overflow. I copied a design I saw right here in the cichlid-forum DIY section. It worked well, and was totally silent, but it couldn't keep up with my pump (rated to 250 gph @ 4' head).


















So, I rebuilt the overflow to skim from the surface, and lowered the tee fitting to the bottom of the outside line. This increased the flow enough to keep up with the pump, but it sounded like an industrial toilet flushing.

I built a "Stockman Standpipe" for it, and this helped a lot, but didn't satisfactorily end the noise. Finally, I wound up with a hybrid design combining elements form the Hofer gurgle buster and the Stockman standpipe. This has reduced the noise to a trickle sound, not unlike a HOB filter, and my wife says "I can live with that." :thumb:










If I get a venturi working on the return line that is capable of priming the overflow in the event of a siphon break, I'll share the details.

Thanks for your advice.


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## KaiserSousay (Nov 2, 2008)

> says "I can live with that."


Well congrats buddy =D> 
I never got those words from mine.
Nice, clean work..really like your media tower..
Very well done.


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## fishyfishyfishy (Dec 24, 2005)

I'm confused...

If you want to go with a HOB filter, why not just go with a HOB overflow box?

Yes, there's a remote chance that during a rare power outage that the siphon won't restart.

But, you can be 100% assured that you will not overflow the tank in that rare event.


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## JALOOS (Sep 6, 2008)

I run a HOB overflow box that feed 2 1 inch lines to my sump. It has a fitting on the top to which I have added the powerhead for priming in the event of a power loss. It has rarely lost its siphon due to power outage or me shutting down the system to do cleanig ect. I actually added a valve to the attachment point on the box so in the event that I want the siphon broken it can be done easy. Although the box is expensive to buy in the first place it is easy to setup and maintain. I have modded it slightly to reduce any noise and add filtration to keep top of my sumps cleaner. I added a large piece of foan filter to the box that was carved out for the 2 standing strainers on the overflow, this cuts down alot of noise and adds good filtering as well. On top of this I run about 2 to 3 inches of fiberfill that I change out weekly to keep foam cleaner and provide alot of filtering and sound deadening. I added a straw down the inside of one of the corners to act as a safety in case the media starts to plug up too much and it will allow water to flow by the sponge and floss as well as giving me a nice audible warning.


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