Homemade Aqaurium Weir Siphon Overflow Box

First off, what is the world is an aquarium weir siphon overflow box?

Well, everyone knows what an aquarium is, and that I like my fish tanks!
Most people are familiar with a siphon – a hose that allows you to drain water out of a container over the side of the container.
A weir is basically a long dam where the water overflows for the full length of the dam.
An overflow box is a type of aquarium filter.

So, basically, I am making a dam, that siphons water out of a fish tank.
The neat thing about doing it this way, is that the siphon won’t ‘break’ when the water level gets too low, as the weir (or dam) will hold the siphon. Quite a clever setup actually. I wish I had thought of it.
I read about this probably well over a year ago. I did a quick search, and found the same site! http://www.melevsreef.com/acrylics/overflow.html

So, with a quick look over their instructions, I completely disregarded them as to measurements, and made up my own. I just wanted the concept.

So, after much scientific analysis, here are my measurements. Yeah, Yeah, I mocked it up in cardboard. I did actually take a measurement! I measured the inside of my 4″x4″x4′ nano tank. The idea is that I will make a ‘stream’ fish tank like nobody else has!


So, from the 1 measurement, I made it square, as an overflow box MUST be BOX shaped, or it’s an overflow rectangle, and, well, we just can’t have that. I started cutting away at my plastic.

This is a high-precision operation I run hear. Silicone my tolerances! I taped the two sides together, and cut them with a coping saw.

After many long, excruciating seconds calculating the flow rate for the whole contraption, I just held the damn thing up to the tank and eyeballed how high I wanted the water to be in the tank and made the weir element that tall.

Here you can see the start of the inside of the siphon element. You can start to see the difficulties assembly will incur, due to the various bits and pieces getting in the way of sealing the seams. It can really only be assembled from the inside out and be able to be sealed. (high tolerances, remember?)

This is what the completed unit would look like. It’s just taped together here, waiting to be cut apart and glued together.

This is what it looks like hanging on the side of the tank. Pretty cool looking, I think. I need to add the outflow pipes yet. But you can get the idea. The water will overflow the weir on the right side, inside the aquarium. The water will be siphoned over to the left side, where it will overflow the second weir into the outflow box.



Remember those high tolerances. Yeah, you know, measure twice, cut once. Don’t let the ruler slide around as you cut. I have a leak. I turned the thing upside down, and filled the siphon area to see if it will hold water. Nope, my work ‘sucks’ air. No worry. 100% Aquarium silicone to seal up the leak. **grin**.

7 Replies to “Homemade Aqaurium Weir Siphon Overflow Box”

  1. Do you route the filter drain pipe back into the tank?

    So this filter only work when the tank level is at a proper height. Sounds like you can’t be using your fish tank for a humidifier then.

  2. This thing will only work when you use a sump. The sump for my little tank will be the 75 gallon tank.

    LOL

    This thing will keep the tank water at the same height, as the sump looses water height. You just keep the sump topped off, and your good. Makes the tanks look always ‘full’.

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