Overflow system

Alright, so my secondary sump has been resealed. I'm letting those welds fuse before I try another water test. Now what to do? Well, you know how I keep talking about how these drainage pipes from my display tank to the sump? Have you ever wondered how on God's earth that works? Well let me tell you sweetheart.

There are a couple options. The first one is an external pump. Pretty much there's a pump behind the tank sucking water out of the display and pushing it toward the sump. From what I've seen this is fairly uncommon and frankly expensive. It's also retarded given the other options which are more or less free.

Option two is called an overflow chamber. It's a pre-drilled hole in your tank. That's right, you have holes in your display tank. In this photo the center column is the overflow. Once the water level gets above the center box's height the water spills over and drains into the sump via gravity. The two other holes are the return holes for water exiting the sump. For most custom made acrylic tanks this seems to be fairly common. Some people even custom cut their glass tanks to have an overflow chamber but I would never risk drilling my own glass tank. Noooo way.

The third option is the most complex and is called an overflow box or weir. I'm going to call it a weir so it doesn't sound too similar to overflow chamber. So a weir is this odd little box that looks like this. It's a gravity/vacuum powered box that sucks water OVER the wall of your tank. That's kinda weird eh? No electricity, no pumps no nothing, just some fancy physics that blows your mind. So lets talk about the weir following along in the picture to the left. The left side of the weir is in the display tank. It hangs over the tank wall so the back chamber (where the drain to sump is) is outside the tank. Now, watch what happens when we pump more water into the display tank from the sump...

So as you can see I've taken the liberty of increasing the water level in the tank. Water has an interesting little quality called "pressure" and as you can see the tank will fill up as high as the water line where ever it can due to the pressure of the water. You'll notice though the water level is NOT high enough to travel through the inverted "U" and flood over into the drainage pipe. And even if it WAS high enough we would be overflowing the display tank because that means our water level is above the height of the tank wall, see?! Alright, moving on. You'll also notice I placed a small amount of water in between the baffles down by the drain. You'll see why in a minute. So right now the water pressure isn't enough to push it over the tank wall. That's because the weir is air pressure from the trapped air in the inverted "U" is resisting the force of the water. So see that little tube at the top? You simply just purse your pretty little lips around that and suck some of the air out! This will decrease the air pressure and there will be less resistance for the water and the water level will rise! This is why it's important to have water down by the drain so when you suck the air out of the chamber there's water on both sides to create a "seal" if you will. You have ultimately primed your weir so it will endlessly pull water above the water line and down into the return pump!

Make sense?! So, this is by far going to be the most complex piece I make. It's most important the weir is 100% air tight, if not the vacuum will leak and the siphon will be broken and no water will drain from the tank! So, I got my keys and took ANOTHER trip to my local plastics dealer (I officially have a "plastics" guy now which is a sad thing to admit). I purchased 40$ worth of acrylic and made my way home.

I don't necessarily feel the exact schematic of my weir is of utmost importance. If you really want to see it let me know and I'll draw it up. But I designed and cut and cut. This was actually the easiest part to cut because all the pieces were 7'' or small versus my 15''-22'' monsters on the sumps. Though, the sides of the weir were a bit complex they didn't give me too much trouble. And here it is!

I'm rather proud of this guy.

Now while it wasn't a very hard piece to cut it was a bit more of a pain in the ass to weld. There was just a lot more pieces and I needed to ensure it was all air tight and that it would properly hang on to the tank wall and yeah. There were more issues. I also have about 10 million solvent stains on the box but I really don't care. It's functional. I'd take a video of it working but... well. It's not as excited as I had hoped haha.

Now have you noticed the front of my weir is black? Looking good huh? I assure you, it's not an aesthetic preference. That's the chamber that will be inside the tank. Which is also where all my lighting is! So, by making this black most all the light will be blocked which will reduce algae growth inside the weir. You have to imagine trying to fish a bunch o' algae out of your inverted "U" must be a pain in the ass, eh? Did you also notice the front black screen is slitted? This will allow for water to overflow without letting fish swim into the weir. Cause I don't think my fish wanna end up in my sump. And even more importantly I don't want my fish to end up in my sump!

So that's it for weirs. I think they're pretty neat!

Day 4

Cost of supplies- 40$
Cost of tools- 30$ (I had to buy some drill bits to drill the air hose hole!)

Total cost of supplies- 400$
Total cost of tools- 110$