Two Overflow Questions!

Augustus · 10/08/2012, 09:17 AM

So I'm moving from my first reef tank, an all in one system, to a drilled tank and a sump.

My tank is a 36x18x24 65g and it has two 2" holes drilled on opposite ends about 3" from the rim and each end of the tank.

My first question is how do I know how much flow can go through a bulk head? I'm assuming there is a calculation out there that will tell me this but I have not found it.

Second I would like to do a bean animal overflow. Since my tank is already drilled and I don't want a giant overflow box in the tank I would like to make a coast to coast overflow in the tank that will flow through the two pre-drilled holes into the external overflow box with the bean animal system. Is this doable? Should I install the bulk heads on the two pre-drilled holes or leave them the way they are? If this isn't a good idea what would be the best way to do a c2c and bean (how best to allow the water to flow from the c2c through the tank wall to the external box? More holes, one giant hole?).

Thanks guys!

Reefahholic · 10/08/2012, 10:34 AM

Most people do three holes on the bean overflow.

2 main drains and one emergency drain, but it's really not needed. I like 3 just in case though.

Ur bulkheads will be backwards for an external overflow. Instead of going on the back of your tank, they will go on the bottom of ur overflow box. However, ur tank is already drilled with probably 1" round holes on the back glass. Most people that do external overflows tend to do longer vertical holes to let the water flow through. I guess it looks better than a typical round hole. They should work though...I don't see why not.

I currently have a bean overflow and it works very well. Mine is internal. If I were to ever do it again, external would be my preference. Why? Because the internal will limit the amount of lighting you can run over ur tank. Example...I have 5-6" of dead space from the overflow box in the back of my tank that light can't penetrate through that well. So instead for the 6 or 8 bulb T5's I wanted to set up, I'm stuck with a 4 bulb T'5 which limits my color options and amount of light. Not to mention coral growth and space in the back of my tank under that overflow box. That's 6" of coral space that I could have had if the box was on the outside.

Good luck, if you have any problems getting ur bean running right, PM me...

Ohh, make sure ur return section is as big as you can afford. Otherwise it will suck dry trying to start up. That was my biggest problem. Make sure ur drains are only 1" below the waters surface...no more.

Good luck!

Augustus · 10/08/2012, 11:35 AM

Thanks for the info and the photos Reefahholic! I agree with your thoughts on the external box. Taking up coral space due to an overflow box is something I wanted to avoid. So on an external your thoughts are to go up through the bottom instead of the back of the overflow box correct? I've attached a drawing I did real quick in paint because I'm at work, so excuse the lack of detail!

So in my drawing you would go up the bottom where "B" is? Also I included a mock up of where the holes are in the tank now. I want to have a small (thinking an inch or two deep) coast to coast overflow in front of the holes currently drilled for surface skimming. How deep would you make the coas to coast overflow box that will reside in tank?

Reefahholic · 10/08/2012, 12:46 PM

Yes, you would drill B.

Like this...

My box is 5.25" deep. 6.25" deep from bottom of euro bracing to bottom of box. 4.50 width, enough to get ur hands in there sideways to work in the box. Like scrub algae, get snail shells out, twist elbows and remove them for cleaning, etc.

I'm guessing on your tank that the 2 holes already drilled on each end are return holes for 3/4" to 1" return lines. I may be wrong though.

Reefahholic · 10/08/2012, 01:00 PM

This is how I would do it, if I did it again, but with more space inbetween the drains.

This is what I was talking about if you have 2 holes on each end. These are returns. The other 3 in the middle are drains. This is internal as you can see though. And this guy doesn't have ball valves like most people do.

On my main drain, I have a ball valve and gate valve. I highly recommend a gate valve on ur main drain. Otherwise, it's very hard to tweak your system and get that water level right. Very difficult with ball valve. I think even bean himself recommends a gate valve now. So much easier.

Reefahholic · 10/08/2012, 01:09 PM

Hope these pictures help you my brother. I'm fixing to go back to bed. I gotta work 12 hours tonight. I'll be around though. Just Private message me with ur questions if you get stuck and I'll do my best to answer them. Good luck!

10/08/2012, 09:17 AM	#1
Augustus Registered Member Join Date: Oct 2011 Posts: 73	Two Overflow Questions! So I'm moving from my first reef tank, an all in one system, to a drilled tank and a sump. My tank is a 36x18x24 65g and it has two 2" holes drilled on opposite ends about 3" from the rim and each end of the tank. My first question is how do I know how much flow can go through a bulk head? I'm assuming there is a calculation out there that will tell me this but I have not found it. Second I would like to do a bean animal overflow. Since my tank is already drilled and I don't want a giant overflow box in the tank I would like to make a coast to coast overflow in the tank that will flow through the two pre-drilled holes into the external overflow box with the bean animal system. Is this doable? Should I install the bulk heads on the two pre-drilled holes or leave them the way they are? If this isn't a good idea what would be the best way to do a c2c and bean (how best to allow the water to flow from the c2c through the tank wall to the external box? More holes, one giant hole?). Thanks guys!

10/08/2012, 10:34 AM	#2
Reefahholic Moved On Join Date: Dec 2010 Location: League City, Texas Posts: 3,974	Most people do three holes on the bean overflow. 2 main drains and one emergency drain, but it's really not needed. I like 3 just in case though. Ur bulkheads will be backwards for an external overflow. Instead of going on the back of your tank, they will go on the bottom of ur overflow box. However, ur tank is already drilled with probably 1" round holes on the back glass. Most people that do external overflows tend to do longer vertical holes to let the water flow through. I guess it looks better than a typical round hole. They should work though...I don't see why not. I currently have a bean overflow and it works very well. Mine is internal. If I were to ever do it again, external would be my preference. Why? Because the internal will limit the amount of lighting you can run over ur tank. Example...I have 5-6" of dead space from the overflow box in the back of my tank that light can't penetrate through that well. So instead for the 6 or 8 bulb T5's I wanted to set up, I'm stuck with a 4 bulb T'5 which limits my color options and amount of light. Not to mention coral growth and space in the back of my tank under that overflow box. That's 6" of coral space that I could have had if the box was on the outside. Good luck, if you have any problems getting ur bean running right, PM me... Ohh, make sure ur return section is as big as you can afford. Otherwise it will suck dry trying to start up. That was my biggest problem. Make sure ur drains are only 1" below the waters surface...no more. Good luck! Last edited by Reefahholic; 10/08/2012 at 10:48 AM.

10/08/2012, 11:35 AM	#3
Augustus Registered Member Join Date: Oct 2011 Posts: 73	Thanks for the info and the photos Reefahholic! I agree with your thoughts on the external box. Taking up coral space due to an overflow box is something I wanted to avoid. So on an external your thoughts are to go up through the bottom instead of the back of the overflow box correct? I've attached a drawing I did real quick in paint because I'm at work, so excuse the lack of detail! So in my drawing you would go up the bottom where "B" is? Also I included a mock up of where the holes are in the tank now. I want to have a small (thinking an inch or two deep) coast to coast overflow in front of the holes currently drilled for surface skimming. How deep would you make the coas to coast overflow box that will reside in tank?

10/08/2012, 12:46 PM	#4
Reefahholic Moved On Join Date: Dec 2010 Location: League City, Texas Posts: 3,974	Yes, you would drill B. Like this... My box is 5.25" deep. 6.25" deep from bottom of euro bracing to bottom of box. 4.50 width, enough to get ur hands in there sideways to work in the box. Like scrub algae, get snail shells out, twist elbows and remove them for cleaning, etc. I'm guessing on your tank that the 2 holes already drilled on each end are return holes for 3/4" to 1" return lines. I may be wrong though.

10/08/2012, 01:00 PM	#5
Reefahholic Moved On Join Date: Dec 2010 Location: League City, Texas Posts: 3,974	This is how I would do it, if I did it again, but with more space inbetween the drains. This is what I was talking about if you have 2 holes on each end. These are returns. The other 3 in the middle are drains. This is internal as you can see though. And this guy doesn't have ball valves like most people do. On my main drain, I have a ball valve and gate valve. I highly recommend a gate valve on ur main drain. Otherwise, it's very hard to tweak your system and get that water level right. Very difficult with ball valve. I think even bean himself recommends a gate valve now. So much easier.

10/08/2012, 01:09 PM	#6
Reefahholic Moved On Join Date: Dec 2010 Location: League City, Texas Posts: 3,974	Hope these pictures help you my brother. I'm fixing to go back to bed. I gotta work 12 hours tonight. I'll be around though. Just Private message me with ur questions if you get stuck and I'll do my best to answer them. Good luck!