Part 4 Flow…and Overflows
So, you’ve thought all this through, and you’ve likely decided your sump should be cheap, and easy, but also effective. You’ve probably settled on an open sump with no baffles, Pond Matrix in a bag, and filter socks.
Next decide what your “turnover rate” will be. Your tank is 300 gallons, and most would agree that you want 8-10 times turnover per hour on a freshwater CA cichlid tank. So, that means you’ll want 3000 Gallon per hour. Your pump, or pumps, need to put 3000 gallons of water into the tank every hour for big 12 inch fish to have some water flow they can be happy with.
So find a pump, or two, that will do that. Some pumps are submersible, and some are not. Submersible is good because they’re silent, and they’ll put some heat in the water, since they just sit underwater in the sump. So your heaters will run a little less. Submersibles are bad because they take lots of space in the sump. (But you don’t have baffles, so what do you care how much room pumps take up. Nothing else is using all that space.) You may not have room under your tank stand for a 125 gallon sump, so you might not want to just put pumps in the sump water. External pumps are outside the tank, usually pretty high quality, and easier to change if you ever have to. But, you also have to drill a hole in the side of your sump, and every hole has potential to leak one day. External pumps normally mean one big one. Submersible pumps usually mean 2 inside the sump, taking up more space, but giving you some redundancy in case of a pump failure. You need to weigh these things, make decisions.
So, let’s say you’ve decided on a pair of nice submersible pond pumps, putting just about 3000 gallons into your tank. Plenty of flow. Now, you have to figure out how to drain 3000 gallons per hour. That shouldn’t be too hard, though. If you know 3000 GPH goes into the tank, then you need to drain…………….3000 gallons per hour! If you drain less than 3000 GPH, then your floor will catch it, which is probably not what you want. And you can’t drain MORE than 3000 GPH (think about that). So you simply look up the drain rate of various sizes of pipe, figure out how many drains, and what sizes they’ll need to be, and be sure your tank has AT LEAST that many holes. If not, you’ll put more holes in your tank, or tell the tank builder to put them, or drain water outta the tank without adding holes (HOB Overflow).
Next, you’ll probably need to drain this water SILENTLY. 3000 GPH of water dropping 4-5 feet into a sump is INCREDIBLY LOUD. Louder than a washing machine, a toilet, a shower. You can’t watch TV, or sleep, or talk on the phone, in a room with that kinda water drainage happening if you don’t do something to silence it.
The way to drain silently is to keep the draining water under siphon. Laminar flow. Non-turbulent flow. With no air going into the drain line. Air makes the noise. The three overflow designs that achieve laminar, non-turbulent flow of water in a drain are Durso, Herbie, and Beanimal overflow systems. Herbie and Beanimal use a finely adjustable gate valve to restrict the rate of drain to exactly match the rate of pump output. They also use “backup”, “emergency”, or “E” drains to ensure there’s a way to drain water if the gate gets clogged, the pump speeds up, etc. To have silent drains, you’ll probably have to drill extra holes for an extra drain or two.
The Durso method was the first silent overflow method and it is still commonly used today. With a Durso, a hole is drilled into a high point of the drain line, and the amount of air allowed to enter into the drain with the water is precisely controlled by altering the size of the air-hole.
Which method should you choose? Well, the Durso needs only one drain pipe. The Herbie and Beanimal need an extra “E” Drain, so that’s more holes, and bigger overflow boxes to hide an extra drain pipe. The Herbie and Durso can still be accommodated by an internal overflow box, so the tank can be flush against the back of the wall. They also need periodic adjustment—the Durso more than the Herbie. The Beanimal, on the other hand, automatically adjusts itself to changes in drain rate and pump output. But, it also requires 3 drain lines—a main siphon drain, a dry “E” Drain, and a 3rd drain that is called…let’s just call it “the backup”. That many drains should probably be run in a horizontal overflow box called a “coast to coast overflow”. Coast-to-Coast overflows are VERY nice because they take up space only along the top of the tank, leaving the floor space of the tank completely open for fish. But, Beanimal drains also usually mean the drain pipes that run to the sump are routed outside the tank, behind the back wall. So, the tank now takes up more space in your house.
If you read MFK all the time, then you probably want to order the absolute biggest tank that will fit in the room. So you might really NEED the tank flush against the wall. Or not.
So, a Durso is easy to plumb, but it might not be totally quiet in your situation. Herbie is dead silent, harder to plumb than a Durso, but can still use an internal or corner overflow inside the tank. Beanimal is as silent as a Herbie, AND it requires no adjustment. But, you’ll probably have to go to the trouble of running a coast-to-coast overflow box, and drains outside the back wall of the tank. Beanimal and coast-to-coast is nicer, but it’s more work to install, and it takes up additional room outside the tank.
So there you go—you DO need a sump. You almost certainly DON’T need baffles in it. And you can make the sump run silent as a grave with a little extra thought and effort. So, save your money, apply for a credit card, or sell something, and order that custom acrylic 450 Gallon you’ve been daydreaming about.
Browse the diy section of this forum, type sump build in the search bar upper left corner. Also check out Diyfishkeepers. com. Glw your sump build. Btw other members will chime in .
