Dual overflow - Which Bulkheads?

[Shirak]

I am not sure the advantage of a backup drain? Perhaps some others will chime in here? My tank has one drain and one return in each of the 2 overflow chambers. That said, this is a FOWLR tank. I have no snails or other things that can climb into the drains and cause blockages.

Well.. my first DT had a single drain and after overflowing the tank multiple times I was ready to chuck it out the window. My new frag tank system has Fiji cube overflows with 2 drains running Herbie style. One is the main drain and the other is the emergency. The single drain on the DT is incredibly noise with sucking air if I don't want to risk it overflowing.. The Frag tank is quiet and you can't hear anything except for a couple minutes when the pump is shut down for feeding and the syphon is restarting.

Never ever again will I run a tank with a single overflow.. even if it's two that are set to run as they were singles with restricting valves to control water down to the sump.

 

[Shirak]

I have a fully setup 55. Snails and all. It is all getting transferred to the 100g within a few weeks. Rock and all. I do plan on putting a cover ontop of the overflows but I see the point if having an oh crap moment. Mind you my waterlevel in the return won't be enough to overflow the tank, nor will the display be able to overflow the sump based on water level into the overflow

Well if it won't overflow if the drains stop draining then I guess that is one less major concern. Is there an ATO that will pump water into the sump if the drains clog and the sump level drops, which will eventually cause the tank to overflow?

 

[Jedi1199]

Well.. my first DT had a single drain and after overflowing the tank multiple times I was ready to chuck it out the window. My new frag tank system has Fiji cube overflows with 2 drains running Herbie style. One is the main drain and the other is the emergency. The single drain on the DT is incredibly noise with sucking air if I don't want to risk it overflowing.. The Frag tank is quiet and you can't hear anything except for a couple minutes when the pump is shut down for feeding and the syphon is restarting.

Never ever again will I run a tank with a single overflow.. even if it's two that are set to run as they were singles with restricting valves to control water down to the sump.

This is interesting as I can shut power off to the entire system and still not overflow anything?

Wait, I think I see now.. What if the return pumps run full on but the drains stop?? Is that where you are going? HMMMM that IS an interesting question.... I have all along gone with the assumption that the drains were the issue.. but in reality I see that it is the returns that will be the actual problem...

 

[JTremonte]

I plan on making an oversized stockman style return. Essentially it is an oversized pipe over a smaller return drain with holes on the side. I plan on cutting slits like the overflow in it. The bigger pipe around it will help with noise. I personally like the stockman design but I'll be oversizing it. I got 4 kids so it's loud in my house regardless.

 

[JTremonte]

I'll have a switch to manually top off. Personal preference. I do have a 5gallon ato container. I'll just install a pump to put into the sump and hit a button. I can afford 3 minutes of my day to hit a button.

 

[JTremonte]

That can only hold so much water where the return is. X water has to fit in the tank. I think thats 4 gallons. Which is nothing for my display water level. As long as x in return pump bay can fit in display I'm good. Same with display fits in sump. Most overflow of display or sump is avoidable if done properly.

 

[Jedi1199]

@Shirak

I can completely see where you are going with this. However, I don't see this as an issue with his, or my tanks.. With the dual overflows, we have a built in redundancy to solve this exact problem. If one drain clogs, the other will still flow. On a SINGLE overflow system, i can see a backup emergency drain not only being useful but almost a necessity!!

 

[JTremonte]

So to finalize. Each overflow will be full drains. 1 emergency, 1 main. I'll T them together and go into sump. Then I'll do a single return that will go on the BACK side of my display. And into the tank. Probably split into the display to shoot both ways for surface agitation.

That's option 2. I'll debate which way I go but with some matching wood / molding I can hide the returns. It ain't a bad option.

It'll solve if 1 does clog, my return won't run dry. With the imbalance of water draining.

Cheers

 

[Jedi1199]

@JTremonte

How large is your sump? I can see the issue that @Shirak is concerned with. If somehow your drains become clogged, the return pumps will continue to pump water from the sump. If your sump is large enough, it could possibly overflow the DT onto the floor.

For example: You have say a 50g sump and a 100g DT.. Your drains stop draining.. the return pumps will continue to pump until your sump runs dry. Can your DT handle an extra 50 gallons of water? Granted, with your dual overflow system this is INCREDIBLY unlikely, but I see where his concern comes from.

 

[Shirak]

This is interesting as I can shut power off to the entire system and still not overflow anything?

Wait, I think I see now.. What if the return pumps run full on but the drains stop?? Is that where you are going? HMMMM that IS an interesting question.... I have all along gone with the assumption that the drains were the issue.. but in reality I see that it is the returns that will be the actual problem...

I have no issue shutting power.. the tank drains a little and the sump holds it. I have a check valve on the return line too but even if it fails or doesn't seal completely the sump has enough space to hold the water in the tank that will return to the sump.

Problem is if the drain stops draining and the tank keeps rising with the return pump going full steam. It will start sucking air into the return pump before the tank overflows.. but the ATO will pump water to the sump which will then pump more into the tank and eventually it overflows. Plus it puts a whole lot of RODI into the system.

 

[Shirak]

So to finalize. Each overflow will be full drains. 1 emergency, 1 main. I'll T them together and go into sump. Then I'll do a single return that will go on the BACK side of my display. And into the tank. Probably split into the display to shoot both ways for surface agitation.

That's option 2. I'll debate which way I go but with some matching wood / molding I can hide the returns. It ain't a bad option.

It'll solve if 1 does clog, my return won't run dry. With the imbalance of water draining.

Cheers

If you decide to go with two drains per overflow, keep them separate all the way to the sump. If you T them together below the overflow you are effectively going back to a single drain. The idea with the two is the main drain has a gate valve to control the water flow down the drain to create a full siphon without sucking air. The second drain is for emergency and left wide open and has at most a tiny trickle of water when the gate valve is set on the main drain. So the pipes need to be separate all the way to the sump for this to work correctly and super quietly.

Look up Herbie style overflow plumbing. The second drain has a stand pipe which is just a tiny bit lower than the water level in your tank.

 

[Jedi1199]

I have no issue shutting power.. the tank drains a little and the sump holds it. I have a check valve on the return line too but even if it fails or doesn't seal completely the sump has enough space to hold the water in the tank that will return to the sump.

Problem is if the drain stops draining and the tank keeps rising with the return pump going full steam. It will start sucking air into the return pump before the tank overflows.. but the ATO will pump water to the sump which will then pump more into the tank and eventually it overflows. Plus it puts a whole lot of RODI into the system.

Yes I see that!!

On my tank, each overflow box is independent of the other. If one shuts off entirely the other takes over. Built in redundancy. That said, if in the extremely unlikely event that BOTH drains clog at once.. 30 gallon sump plus 5 gallon ATO = A BIG mess on the floor....

 

[JTremonte]

I can put the emergency in the refugium them no problems. My sump is 36g. But where the return pump is, only holds 5 gallons I want to say. Maybe a little more. Without a ato I won't run the risk.

 

[Jedi1199]

I can put the emergency in the refugium them no problems. My sump is 36g. But where the return pump is, only holds 5 gallons I want to say. Maybe a little more. Without a ato I won't run the risk.

You are not seeing the whole picture... Your return "Chamber" may hold 5 gallons.. but the sump holds 36g. Much of that water is suspended above the equilibrium line as gravity is what makes a sump system work!

Your sump will seek equilibrium. the pumps will continue to pump until there is no water left for them to pump..

Picture this: Your return chamber holds 5g. Your sump holds 36.. your ATO holds X.

The pumps will pump ALL of the 5g chamber they sit in, PLUS ALL of what the ATO pumps in as it tries to compensate for what it thinks is evaporation, PLUS all of whatever amount of the 36g it takes to reach the top of the baffle between the main sump and the return chamber. You could easily add 20-40g to your DT in the event of a failure.

 

[Jedi1199]

Let me show you visually what we are talking about here...

This is my sump. It holds about 30g of water.
on the very far left is where water enters from the tank. Notice it is full to the top?

From there it flows over into the mechanical and bio filtration.. Do you see the water line?

Now, do you see the baffle between the last chamber and the return pumps? That is the lowest point in which water flowing from the previous chambers will overflow into the return pump chamber.

If your drains stop working, your return pumps will drain the sump to that line, PLUS all of the water in the chamber where they sit. AND all of what the ATO adds as it attempts to replace what it thinks is evaporation..

Can you see now how it is possible to pump an extra 30 gallons into the DT?

 

[Shirak]

I guess it would depend on how each individual sump is set up. Mine is pretty much wide open so it will drain almost completely. I don't have a baffle that will keep the sump half full while the return pump area will drain down. I do have plans for a new DT and sump etc so these are good thoughts for my next build!

 

[JTremonte]

Based on where the logo is. Will determine how much water is in the middle compartment. Plus a small additional because it will overflow that, up and over through the bubble trap. Then to the bottom side of my return compartment. If water falls below where that logo is. The only water left is in that compartment. I should roughly be only 1" MAX above where it overflows into the return chamber.

also to add I'll be manually adding water instead of an ato.

 

[JTremonte]

Mind you that is if that adjustable baffle actually holds the water in the middle chamber and doesn't slowly leak. Which I have an automatic shutoff I could implement in the display that can plug into the return pump.

 

[Weasel1960]

I have actually been contemplating the Aqueon 120 with 2 overflows. If doing 2 returns in one overflow and the emergency return in the 2nd overflow the second overflow would not have much water movement if any at all. Wouldn’t that cause water quality issues?

 

[Jedi1199]

I have actually been contemplating the Aqueon 120 with 2 overflows. If doing 2 returns in one overflow and the emergency return in the 2nd overflow the second overflow would not have much water movement if any at all. Wouldn’t that cause water quality issues?

We are discussing a worst case scenario here. It is VERY highly unlikely that BOTH drains will clog simultaneously.

I do NOT have an emergency drain on my tank!!

The reality is that the way my tank is set up, with dual drains and dual returns, it is set up with a built in redundancy that makes an emergency drain irrelevant.

The way the OP tank is set up is different, but similar. Instead of dual returns, he has one that feeds a diffuser bar system (see his pictures posted). However he STILL has TWO drains into his sump.. therefore he still has the same redundancy built into his system that I do.

Your question about degrading water quality is irrelevant. The emergency drain is exactly that.. an "Emergency Drain"!! It is not intended for continual use or in any other way to be used for the sustained use of your overflow drain system. It is simply there to be used as a way to avoid the accidental overfilling of the DT. Nothing more.

Set up your dual overflow boxes exactly as designed.. 1 drain and 1 return in each box.. simple effective and safe.