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**

Florida Keys Sunset Festival

Key West has a “Sunset Festival” in Mallory Park off the north end of Duval Street. There are a bunch of street performers and such, but what I like, is the sunset.

A normal sunset photograph during the Sunset Festival in Mallory Park in Key West, FloridaA ‘normal’ sunset photograph during the Sunset Festival in Mallory Park in Key West, Florida.

I got out one of my fancy camera filters and took this photo with the 8 point star filterI got out one of my fancy camera filters and took this photo with the 8 point star filter.

Here I used my Here I used my ‘Sunset’ filter, but I think I had it in upside down – the darker part was up.

The The ‘Sunset’ filter can really make a sunset pop. Posted by Picasa

Hydor Bioflo Small Aerobic Filter

I recently purchased a Hydor Bioflo Small Aerobic Filter from Big Al’s. It looked like it could be a really good product. I have a problem with the top of my planted tank looking like like the water sitting in a dirty pot for 3 days… you know, that nasty looking scum on the top? Well, this product says that it “Eliminates white line effect and surface grease.” Sounds great, right? I am disapointed. While the “surface grease” has drecreased, it is still very much there. I gave it a chance. It came up lacking. Time to hack it to make it work better.

Hydor Bioflo Small Aerobic Filter sitting on the top of the water.

This is what the gizmo looks like in my tank. I think this is even what the water level should be from the photo on the box. Ok, maybe it is a little low. One of the problems with the filter I think, is that the water doesn’t actually flow through the sponge. It flows around it.

Hydor Bioflo Small Aerobic Filter peices and parts

Here are the major assemblies for the filter. The lower right piece is the outer housing which rotates around, spinning the filter that slips over it. The top center peice is the filter foam. The lower left assembly is the turbine and planetary gearing(that is the right name for this gear type, correct?).

Hydor Bioflo Small Aerobic Filter peices and parts

Here you can see that the housing has a very wide backplate. I think that the backplate is blocking much of the water flow through the sponge filter because it covers about half of the back surface area. The little round circles you can see in the reflection are molding lines.

Modified Hydor Bioflo Small Aerobic Filter to increase water flow

Here you can see the modifications I made to the backplane. I used the molding lines as a guide and drilled holes through the filter housing backplate. I am hoping that this will increase waterflow through the filter. I am going to give this modification about a week or two trial run and see if I can tell if it worked by examinging the filter foam.

Another modification that I thought of is modifying the shape of the teeth of the filter sponge. I think that makeing them cupped so that they actually cut into the water, encircling a small bit of the water surface before submersing will greatly increase the effectiveness of the “degreaseing” capabilities. Ths modification will also quickly submerge any floating food too – so it isn’t perfect (if it works as intended). I will wait and try this other modification after my 2 week trial on the existing modification. The larger version of the filter may be more effective as well.

 Posted by Picasa


Here is where I run the hose from my CO2 bottles into my Eheim canister filter. The canister filter holds the CO2 in the water for a lot longer than any other way I know of. This greatly helps getting the CO2 to diffuse into the water. I used one of the nipples that come with the really thin air hose to splice it with the thicker hoses. I drilled a small hole in the center ot the green plastic sheild and stuck the nipple into the filter pickup. The canister filter pump breaks up the bubbles into tiny little bubbles that stay in the tank for a while even after they are pumped back into it. Posted by Picasa