Back Wall Bulkhead Overflow Options

[jharding08]

I am trying to set up a 36"x12"x12" drilled acrylic tank as a frag tank. It has no overflowbox/chamber, just a bulkhead on the top left corner of the back wall.

What is my best option for an overflow in this situation. I have a sump that the water drains to.

Should I put in weir for surface skimming or can I tune a durso to work with a Mag 5 return pump?

Right now with a Mag 5 and a SCWD, I put a street 90 on the tank side of the bulkhead and a T with a cap and 1/4" john guest fitting with RODI tubing and adjustable air valve. I am running flex pvc drain pipe about 1" below the water surface in the drain chamber of the sump, but am still getting back pressure in my drain line which causes the water in the tank to rise to just above the street 90 before the pressure is released and the water flows all the way down to the bottom of the street 90 elbow where it acts like a siphon (gurgling) before the water level starts to rise and repeats the process over and over. I have a slight "S" in the drain line to get into around the stand and into the sump below the "T" on the bulkhead.

Is the water level flucuation because of the volume of water that is acting on the drain line (tank volume vs. overflow chamber volume)?

[potterjon]

It sounds like your tank was drilled for a built in overflow box. I had a 29 gallon frag tank like that years ago. They need a custom stand if you want to hide the pipe. But if you don't care about seeing the pipe, the tank just needs to be pulled away from the wall to accommodate the plumbing. I can't really tell what is going on with the plumbing from the description but it sounds like maybe you need a vent somewhere in the line.
Pictures would help a ton with a question like this. This website may have what you are looking for as far as an overflow box.
http://www.glass-holes.com/

[jharding08]

Here are some photos of the tank:

Plumbing Locations (note height of drain bulkhead in tank on back wall)


Drain with street 90 elbow and screen


Top view of Return line, SCWD and Drain Durso


Drain Standpipe


Water Level of tank with MJ1200 running as return pipe and durso air valve adjusted as far down without creating back pressure


Drain pipe. Notice gently "S" curve to get into sump


So as of right now, I have to run a MJ1200 as my return pump, just so the 1" durso standpipe can handle the flow and provide some water level below the top of the tank. This pump says it runs 250 GPH. I have my SCWD set up for a Mag 5, which is rated at 500 GPH. With the SCWD, conversion to 3/4" flex PVC return line and 3 feet of head, what should I be getting as my return flow?

Right now, my overflow cannot handle the Mag 5 thru the SCWD. I get fluctuating water levels and cant adjust the air valve on the standpipe enough to get it to regulate to a constant water level.

Based on the pictures, should I install an overflow box? Will it help handle the Mag 5 and also aid in surface skimming? Maybe something like this - http://premiumaquatics.com/products/...4w-3d-5t.html?

Problem is, that when I install it, I will probably super glue it. Then at that point, I wont have access to my bulkhead on the tank side. Also, I will probably have to glue it so the teeth touch the top of the tank, since the bulkhead is so high. Will it even work?

Thanks for your help.

[potterjon]

Ah that's much better! Nice looking tank.
I am not sure that I can answer your exact question but a maxijet 1200 is a obviously a tiny return pump, especially with head height. The overflow box would probably help you establish a gallon per hour rate to match to a return pump, but with it set up without it I would guess that the rate would just be equal to whatever pump you have as a return. This one may be over my head.
I do see that you already have a vent on the drain line.
I can say that the overflow box I installed had four sides on it and was secured with the bulkhead itself. If you install an overflow box, that should help you know exactly what return pump to match it with after you do the math for loss due to head height. If I am understanding your question correctly.

[potterjon]

Also, a durso stand pipe is the pipe plumbed into the drain. Not the return.
Here is a pic of a durso stand pipe.

https://www.google.com/search?q=durs...2F%3B252%3B393

If you look up the pump specs online, you will find charts that state flow adjusting for head height.
If you installed 700gph overflow box, then you could use a pump that is equal to 700 gph at that established head height. Here is a link to mag pump head height. It doesn't specify the size pipe though. Maybe someone else will chime in.

https://www.aquacon.com/DannerMag-DriveWaterPumps.html

[jharding08]

Originally Posted by potterjon

Also, a durso stand pipe is the pipe plumbed into the drain. Not the return.
Here is a pic of a durso stand pipe.

https://www.google.com/search?q=durs...2F%3B252%3B393

If you look up the pump specs online, you will find charts that state flow adjusting for head height.
If you installed 700gph overflow box, then you could use a pump that is equal to 700 gph at that established head height. Here is a link to mag pump head height. It doesn't specify the size pipe though. Maybe someone else will chime in.

https://www.aquacon.com/DannerMag-DriveWaterPumps.html

I found some overflows that are 700 GPH max, and they are retrofit. So I could just drill a bulkhead hole and run it through the overflow and the back of the tank.

I guess I am not sure of how the overflow will make my Mag 5 work with the current drain setup, if I am just putting a box over the drain and having the water flow over it. Wont it still be the flowrate of the Mag 5?

[potterjon]

Yes you may be correct about the box not changing the flow rate. I am not really sure about that one. I don't think you have to drill for a bulkhead though, because you already have the hole with the bulkhead in it in the back left hand corner of the tank.
If I were you I would email www.glass-holes.com and see what they have to say. Or just give them a call. I understand your question but I don't know think I can answer it. Maybe someone else will chime in with a little more experience.
I guess the question is
"Does an overflow box regulate the flow rate to the sump or does the return pump?" Sounds simple enough but now I am all confused. And I think the answer is, the return pump determines the amount of flow but it cannot exceed the rate of the overflow box, if that helps at all.

[jharding08]

Should I upsize the bulkhead to the 1.5"? I would like to run the Mag 5 at full speed/flow.

[potterjon]

I don't honestly know if that is necessary but I don't think it is. If you look at the chart your mag 5 will not be pushing that much water at that head height.

[jharding08]

I was thinking of upgrading the plumbing to 1.5", but leaving the bulkhead at 1" to see if it works like BeanAnimal's overflow does. Granted he uses three drains, but it can handle over 2000 GPH. I am just looking for less than 500 GPH.

Any feedback on if that will work? I just dont think running 3 drains on a 25 gallon tank is necessary, is it?

Also, should I have the end of the drain pipe below the water line or above? Even with the 1" plumbing and the 275 GPH pump, I have it adjusted so that it is right below the top of the elbow, but every once in a while it drains to the bottom of the elbow, and then refills. Still back pressure?

I guess I can still upgrade to a 700 GPH overflow and 1.5" bulkhead. That should handle it right?

[woodnaquanut]

Using your current BH, the OF box will not improve the flow. It will give you surface skimming. This is valuable.

With one drain you really can't do a full siphon without getting the flush-slurp cycle. That won't hurt anything if you don't mind the noise.

I'm not sure your drain has enough capacity for a Durso. The fact that you are getting the siphon started leads me to believe it doesn't but this might be a function of the elbow turned down on the wet side of the BH.

Just for grins, how about turning the elbow to facing up, not down. Run the Mag5 and open the drain air valve all the way. If you don't have the room for that, how about just the strainer on the BH? I've seen this lots in LFS tanks.

Either of these two setups will give you a little surface skimming.

I would NOT glue an OF in. Especially if you can't get into it from the tank side. There will be times it needs to be cleaned out!

[jharding08]

Originally Posted by woodnaquanut

Using your current BH, the OF box will not improve the flow. It will give you surface skimming. This is valuable.

With one drain you really can't do a full siphon without getting the flush-slurp cycle. That won't hurt anything if you don't mind the noise.

I am hoping to quiet the drain as much as possible. I bought a retrofit overflow box that is a full box and you drill a hole and then feed the bulkhead through the OF and the back of the tank to attach it.

Originally Posted by woodnaquanut

I'm not sure your drain has enough capacity for a Durso. The fact that you are getting the siphon started leads me to believe it doesn't but this might be a function of the elbow turned down on the wet side of the BH.

If I move to 1.5" pipe with a 1" bulkhead, will a durso work then?

Originally Posted by woodnaquanut

Just for grins, how about turning the elbow to facing up, not down. Run the Mag5 and open the drain air valve all the way. If you don't have the room for that, how about just the strainer on the BH? I've seen this lots in LFS tanks.

I am not sure I have enough room to turn the elbow up. I will try the Mag5 with just a strainer on the bulkhead and the air valve wide open. Won't that lead to slurping noises? Should I have the drain under water in the sump? (~1")

Originally Posted by woodnaquanut

Either of these two setups will give you a little surface skimming.

I would NOT glue an OF in. Especially if you can't get into it from the tank side. There will be times it needs to be cleaned out!

The OF box I ordered should help with surface skimming, but not sure how much of a drop from tank water level to OF water level I can get with the bulkhead mounted so high in the tank, is a water level drop important?

I plan on moving to 1.5" pipe and keeping the 1" bulkhead for now, possible moving to a 1.5" bulkhead as well. Not sure how the overflow box is going to work out, but I am going to give it a try. I would need to keep the downturned elbow to at least get some water drop from tank to overflow box.

[jharding08]

I have the tank running stable with a MJ1200 and my 1" bulkhead/plumbing , with no elbow or strainer on the tank side and the air valve wide open.

The water comes up about 3/4 of the way on the bulkhead, but stays pretty consistent. No flushing or gurgling.

I am going to upgrade the durso and drain piping to 1.5" this weekend. I will look for a 1.25"x1" street elbow for the intake, but first I want to make sure the 1.5" drain can handle the Mag-5

With the current MJ1200 and the 1" bulkhead (no street elbow on tank side), the water is about 1/2" from the top of the tank.

The overflow that I got (rated at 700 GPH) has the grooves drilled to about 7/8" from the top of the overflow.

So, if I put the overflow in with the current pump and bulkhead placement, the water wouldn't fall over the overflow, since the bottom of the grooves are lower than the current water level with the bulkhead.

If I use a street elbow, I will be able to drop the water level hopefully below grooves on the overflow, but how much of a drop from tank to overflow should there be? Will I need to cut the top of the overflow off too? The bulkhead is just mounted way too high.