Plumbing Dual Corner Overflows

[Hugh Mann]

I am beginning the stages of setting up a 265 gallon aquarium, and have some questions regarding the plumbing.

What diameter of pipe should be used? How do I know which to use to suit the flow rate of the return pump? I would imagine if I go too narrow I risk overflowing the tank/draining the sump completely.

With dual overflows, should they plumb separately into the sump with different socks, or connect into one main line?

For the return, how does that get set up? Just up the back of the tank and over the top? Would it make a difference at all if I had it flow straight down, forward, or sideways?

When I got it, the overflows had long pipes coming up from the drilled holes to top of the overflow section, what is the purpose of that?

Tips, tricks or other suggestions?

 

[DCR]

It sounds like a standard Marineland Tank. I think they typically come with bulkheads/holes for 1" piping in the overflows. If you use them as "Durso" type overflows which are the standpipes you refer to, you may be a little limited on flow with only 1" pipe and it may be noisy. The pipes are there to minimize the water fall over the weir and the noise that comes from it. You want the water level in your overflow box to only be maybe 1/4" to 1" max below the water level in the tank.

There are often a second set of drillings in each overflow box for returns (often 3/4"). Some people convert these to full siphon drains in what is called a "Herbie" where you have two drain lines in each overflow. On the smaller drain, the liquid draw is completely submerged about 6" below the overflow and you throttle the flow with a valve on the outlet. It is referred to as the full siphon. You throttle the flow down to still let a small excess go through the normal Durso overflow. You can get a lot more flow with the full siphon than just the Durso and it is much quieter. You then have to plumb your returns over the top. I would suggest you read up on the Herbie if you wish to use one. They can be difficult to balance the flows with two overflow boxes.

You do not want to submerge the returns much below the surface because if your return pump stops, it will siphon down to the depth of the return and possibly flood your sump. I like to direct them horizontally across the water surface and just slightly below the surface to create some agitation/ripples and air exchange with the water. Some people put eductors on the end to increase the circulation in the tank.

Generally it is best to route the drains separately to the sump. If you go with full siphons, I would put those to the two socks and then just slightly submerge the overflows to the skimmer compartment.

The alternative is to scrap the internal overflows, plug the holes and go with a ghost overflow like Modular Marine and others sell. These take up less space, provide very long surface skimming and are generally preferable to corner box overflows. They generally come with a third overflow which is used as an emergency overflow (called a Bean Animal for its creator). The downside is that you would have to drill the back panel of the tank for two relatively large bulkheads that connect the inner and the outer box

Suggest you do some research. There are extensive infomative threads on RC and here on overflows.

 

[Hugh Mann]

That is a ton of information, thank you. Much reading is required on the subject for sure.

It's not a standard Marineland, or so I was told. Guy I bought it off said he had it custom made. Overflows only have one hole in each, I'd guess about 3" looking at them. Certainly doesn't seem as straightforward as I had assumed it would be.

 

[DCR]

If the holes are about 3" in diameter, it is probably made for a 2" bulkheads and is just an overflow. They will carry a lot of flow. I would try to match the drain pipe size to the bulkhead. If there is space in the overflow box to put a U-bend or two elbows on the top (with vent hole on top) it will be much quieter. An open top pipe will be very loud. I would even consider reducing the stand pipe size if it allowed for a U-bend on top.

Your only other option is going to be ripping out the corner overflows and going to the ghost style (Modular Marine) external overflow box

 

[92Miata]

Its also possible that the previous owner was running a Japanese style standpipe/return

https://www.reef2reef.com/threads/japanese-style-reef-tank.745241/post-7806495

 

[ca1ore]

Pictures would help.

 

[Hugh Mann]

I have the old stand pipes, just a straight piece of 1" pipe widened at the bottom to fit the bulkhead. Seems like that would be quite loud to me, if simple.

Each overflow is a 12x10x16 triangle.

I definitely don't want to be making any modifications to this tank, drilling holes or ripping out overflows. Can't take the risk of damaging the tank, wouldn't be able to afford to fix or replace it. Because of that, I am thinking the Durso style standpipe.

I'm wondering though, would a person be able to do a sort of hybrid Durso and Herbie? By which I mean use the two standpipes, but join them into one to pass through the bulkhead. Would there even be a point to that?

 

[DCR]

You can't really combine a gravity overflow with the full siphon or it will destroy the full siphon and its purpose. The valve would also have to be inside the overflow box. I would stay with the Durso. You can also do what is called a Stockman standpipe which works like a Durso but uses and oversized cap. It might work if you cannot get the U-bend on the Durso to fit inside the overflow box, although the box seems fairly large.

 

[Hugh Mann]

You can't really combine a gravity overflow with the full siphon or it will destroy the full siphon and its purpose. The valve would also have to be inside the overflow box. I would stay with the Durso. You can also do what is called a Stockman standpipe which works like a Durso but uses and oversized cap. It might work if you cannot get the U-bend on the Durso to fit inside the overflow box, although the box seems fairly large.

Good to know. Yeah, I've got plenty of room for the u bend of a durso. What about pipe diameter? The old one was 1", but I hear 1.5 is the most common. Any reason to not use 2", since I have large holes drilled?

 

[DCR]

Most tanks have 1" drains, but a 2" would carry a lot more water an would be quieter. The only downside might be connecting it into your sump if you plan to use socks, but even that might be workable. Just something to consider. This assumes the bulk head is 2" (which fits in a 3" drilling)

 

[SteveMM62Reef]

I use SDR21 PVC pipe for my overflow Durso. It's thinner than Schedule 40 "better flow," and fits the Schedule 40 sockets. Also I only glue it at the bottom, I never glue the upper fittings. I'm not a fan of using PVC pipe off the bottom of the bulkheads. I knew someone who was trying to pull a pump, the union was stuck, he cracked the bottom of a 220 gallon tank! Also I would use two return pumps for each of the corner returns, if one fails, you'll still have flow. likewise, use two separate power supplies off of separate GFCI, and Breakers. like Danner/Supreme Pumps, and you can get them with really long cords.

 

[ca1ore]

I am beginning the stages of setting up a 265 gallon aquarium, and have some questions regarding the plumbing.

Based on your picture, either the tank is not a ML265, or the overflows were added in afterward.

What diameter of pipe should be used? How do I know which to use to suit the flow rate of the return pump? I would imagine if I go too narrow I risk overflowing the tank/draining the sump completely.

Depends a bit on the flow you are trying to achieve. If it were my tank, I would run both corners as open channels, but I'd try upsizing the stand pipe to 3" PVC. That way you can minimize the water/air mixing which is what makes the noise. Alternatively, go with dual 2" stockman pipes. They are pretty easy to make.

With dual overflows, should they plumb separately into the sump with different socks, or connect into one main line?

I always prefer separate lines for redundancy.

For the return, how does that get set up? Just up the back of the tank and over the top? Would it make a difference at all if I had it flow straight down, forward, or sideways?

Over the back rim - use black PVC fittings and it blends in pretty well. Most folks direct flow with things like locline. On my system, since I need every GPH I can get form my pump, I just flow it straight down behind the rockwork.[/QUOTE]

When I got it, the overflows had long pipes coming up from the drilled holes to top of the overflow section, what is the purpose of that?

I think somebody answered - its to minimize the waterfall sounds.

Tips, tricks or other suggestions?

Important to get the tank level when using dual corner ovwrflows.

 

[Hugh Mann]

It's not a Marineland tank. Guy I bought it from told me he had in custom made by a fellow in Alberta. Don't even want to think about what it cost to bring to BC.

Definitely want this thing to be relatively quiet. My 55 is noisy as heck with all the HoB equipment. I don't need a huge turnover, lots of the fish I want aren't huge fans of high flow, minimal corals. I'm leaning towards a durso style, just for simplicity, I don't know if I'll be able to fit a 3" durso, but fortunately pvc is somewhat cheap. But whatever I do, it has to have some sort of screen or some such over the intake. I've got an eel, and I hear they are notorious for getting into overflows.