Understanding Overflow Boxes

[blabadie]

If you have just the surface skimming box in your tank and you siphon directly from that box into your sump, will this work? How is that any different than siphoning into another smaller box and then into the sump? Can someone please explain this to me, and possibly explain how to get the overflow process started?

Brandon

 

[blabadie]

tee hee. I actually now understand... the box you siphon into is split into two parts... makes sense, sorry!

 

[ikon]

the reason for the small box on the other side of the tank is to keep the other end of the u-tube constantly submerged, creating a reliable constant siphon.

although, i cant think of a reason why you couldnt just extend the other side of the utube all the way down to your sump, as long as you keep the other end submerged inside the sump at all times. but i figure that the small box is more reliable because the utube would be less likely to become un-submerged (therefore losing the siphon).

you should test it out

as far as starting the siphon, run a small airline tube (the kind that connects to an air pump) up the u-tube to the halfway point, then turn your return pump on. as the water starts to climb inside the utube you will see an air bubble created. this is where you want the end of your airline tube to be. when the air bubble happens, start sucking on the other end of the airline tube until the air bubble dissappears. at this point you should have a constant water siphon inside the utube with no large air pocket. small air bubbles are common and okay, just keep an eye and make sure they dont grow into a large air pocket. if a large air pocket occurs, usually siphon loss follows and your tank overflows.

its a delicate balance but once you figure it out you can control it.

 

[blabadie]

so, if I would build a 1/2 inch pvc pipe in the shape of a "U" and use that to create a siphon, I could possibly get this to work right? I would essentially attach tubing to the end of the pvc "U" and run it to the bottom of my sump. The pvc end and the tubing end would stay under the water. Would this work? I am still slightly confused at how the siphon can keep siphoning if it has run out of water in the overflow box. If the overflow box would empty, wouldn't the siphon stop? Also, the return hose I am using is about 1/2 inch in diameter. Does the siphon need to be larger than this?

Thank you,

Brandon

 

[ikon]

firstly, yes you could build a utube out of pvc and both ends would have to stay submerged.

the size of your return pump (GPH) will determine the diameter of pipe you need to use for your u-tube. since its a nano, i think 1/2"-3/4" would be sufficient.

you asked "If the overflow box would empty, wouldn't the siphon stop?"...yes, but the overflow box will not empty if its built properly. to build it properly, you must have a large enough surface area over which the water can flow into the box. again, the size of your return pump will determine how much surface area you need. in a nano, it wont have to be that big. once the water begins to overflow into the box, it will keep a constant water level, usually about 1-3" deep. your u-tube will be submerged below this, ideally 1/2" above the bottom of the overflow box.

all of this is hard to imagine without seeing it first hand. i suggest you build it and try it and if you have specific issues post em

 

[blabadie]

I built one of these. I don't know if I fully understand how I should get it running, but i am trying to make it work as best as I can. Pics to come...

 

[blabadie]

Ok, so it is up and running, but every time it reaches the point where it needs to siphon out water it makes a very loud blurp blurp sound and air, not water, is being pushed in to my sump. I haven't sealed all of the joints yet. I don't know if that is the issue, but I am not to sure what to do.

Brandon

 

[ikon]

did you run an airline tube into the top of the "U" and suck the air out?

 

[blabadie]

Yes, but it doesn't work well that way, I can't seem to get it to siphon like that. I've decided to run an airline, that I've siliconed to the top of the cap on the "T" part, from the siphon so I can suck the air out that way. This will make it a lot easier and sucking out the air from this point proved to be the only "safe" (safe, as in, no water on floor) method. This is really awesome, because my overflow box AND my siphon worked during my test trials. It's all DIY!! It cost me less than $10 too.

Brandon

 

[blabadie]

So, it worked in the bathroom, but I can't get it to work on the stand. Here are pics, maybe someone has some suggestions?
From the front without the tank there:

From the back:

I've tried putting a small air tube into the "U", I've tried sucking from the back, I've tried sucking from the top of the cap, and I've tried plugging the hole on the cap and starting a siphon (this works, but when you let go, it stops). The whole set up is really great, but I just can't get the siphon started like I could in my bathroom. The set up in my bathroom was a straight drop to the bucket I had, and in the situation with the stand, it curves to the right before dropping down, would this affect the flow? It doesn't seem like it would. It's not as if it is going back up... any suggestions?

Brandon

 

[blabadie]

If you look at the picture I posted of my pvc piping and how the whole contraption works, well I finally got the siphon started today and I am so happy! It just needed to be tipped to the right to allow gravity to work more on the actual siphon itself. It's perfectly balanced and it's working amazingly. If anyone needs to build one for a nano, I'd be glad to let them know how I did it!

Brandon