Tank Design / overflow and return question.

[dreamcatcherr9]

Internal vs External overflows, I understand (I think) most of the pros and cons. I’m leaning towards internal.

Internal overflows I notice have different amount of holes drilled for bulkheads. Some have 2,3, 4 maybe even 5.

1-3 drilled holes for bulkheads are for drainage to sump.

1-2 drilled holes for bulkheads are for return lines that can be single or split (for single or dual pump).

Am I good so far.

I notice some tanks (with internal overflow) have return line bulkheads drilled into back on tank (far left and right side).

Am I correct (in what I am seeing)? Does this have an particular benefit (better flow)?

Was this just because people drilled additional holes to an existing tank (than only had 2-3 holes in internal overflow and they wanted to do Herbie or bean / animal style plumbing)?

Just curious, and I am looking into having a custom sized tank made. I can pick the overflow style, drilled holes amount, size and location.

Any options and advise is appreciated!

 

[Jaebster]

I cant answer all of your questions but I think those people with 1 center overflow box that have top left/right holes drilled is for the purpose of the returns.
Many people think that the overflow box distracts from the DT due to size, so they want the smallest center overflow possible, which means no return lines plumbed through the overflow and only drain lines... thus the returns are externally plumbed from the outside 2 top corners.
I can say that the center overflow box on my 900xxxl is huge because it needs to accommodate more plumbing consisting of 2 return lines and 2 drain lines.

 

[LDog74]

External will give you more room in the tank. However, the tank will have to be extended away from the wall 4"-6". I am currently have a new tank mfg and I went with external. The room and seamless flow inside the tank is more important to me. Internal was going to protrude 7" x 19" inside the tank, that is a lot of space.

 

[dreamcatcherr9]

I would have preferred closer to wall, hence internal overflow. I was asking for a slightly wider tank, to help make up for loss of space inside.

I was going to ask for 5 holes drilled inline (to take up the least amount of depth space, but add more internal skimming from overflow box?).

My major concerns are leaks! I’ve never had a sump before (and never plumbed a tank before). I thought in the event of a leak, accessing and repairing would be easy preformed from under the tank, without having to pull it away from the wall (?).

 

[NautiTang]

If you go with the returns plumbed in on the bottom you can access from underneath as you stated you prefered but the corner return design would have less pressure on it as it's not as deep in the water and give you a better flow speed without having unsightly pipes inside the tank. The corner returns could also be accessed relatively easily I would think as they wouldnt be too far from the edge, as long as it's not sitting with a wall on the sides of the tank as well. This way you can also keep your box relatively small with only 2-3 drainage holes depending on style you chose and be able to reach those BHs from underneath. Hope this perspective helps.

 

[dreamcatcherr9]

If you go with the returns plumbed in on the bottom you can access from underneath as you stated you prefered but the corner return design would have less pressure on it as it's not as deep in the water and give you a better flow speed without having unsightly pipes inside the tank. The corner returns could also be accessed relatively easily I would think as they wouldnt be too far from the edge, as long as it's not sitting with a wall on the sides of the tank as well. This way you can also keep your box relatively small with only 2-3 drainage holes depending on style you chose and be able to reach those BHs from underneath. Hope this perspective helps.

Thank you for the perspective. You actually hit one of the issues bullseye. The tank would not only be against a wall, but have small walls to the side (72” would fit in perfectly); but as you suspected, gives me almost zero access to sides and back. I don’t kind the internal overflow box look. Though I will say I think the smaller box inside tank used for external overflow box has some other value.

With internal tower overflow boxes, I’m thinking the water sitting in the bottom of the box doesn’t get circulated well (?). Creating a dead space? With external overflows with a small internal box, I don’t picture that happening?

 

[NautiTang]

This isn't the reply that you hoped for but here goes; it depends on your power head configuration but you would likely have lower flow areas near any type of corner.

 

[dreamcatcherr9]

This isn't the reply that you hoped for but here goes; it depends on your power head configuration but you would likely have lower flow areas near any type of corner.

Even with power heads and wave makers? That kind of doesn’t make sense either?

 

[NautiTang]

Lower flow not dead spot. Although your lowest flows may be underneath your rockwork.

 

[Crustaceon]

For perspective with my 55g, I’m drilling one larger hole for an overflow box that’s rated at 800gph and two smaller holes for the dual return pumps I plan on running for redundancy. These will all be in the back panel because I have easy access behind the tank. In reality, I’ll only push about 400gph into the tank and out of the overflow, so a little over 4x tank volume turnover through the sump.

 

[ca1ore]

If you can manage it within your room, an overflow through the back wall is so much better than taking up all that internal space inside the tank by going through the bottom (plus you only need to have about 5” of clearance behind the tank). Latter just seems so 2005 LOL. Internal low profile skim box can also be much larger, but still unobtrusive, to effect better surface skimming. Plus, I just don’t like putting holes into the bottom of my tanks anymore.

 

[dreamcatcherr9]

If you can manage it within your room, an overflow through the back wall is so much better than taking up all that internal space inside the tank by going through the bottom (plus you only need to have about 5” of clearance behind the tank). Latter just seems so 2005 LOL. Internal low profile skim box can also be much larger, but still unobtrusive, to effect better surface skimming. Plus, I just don’t like putting holes into the bottom of my tanks anymore.

Ok. I’m leaning external now. And the EMS 32” is catching my eye (for my 72” long tank).

Side note, that’s a beautiful tank. What dimensions is it? What who is the maker / manufacturer? Please share!

 

[ca1ore]

Ok. I’m leaning external now. And the EMS 32” is catching my eye (for my 72” long tank).

Side note, that’s a beautiful tank. What dimensions is it? What who is the maker / manufacturer? Please share!

EMS would be a good choice. I went with the 32” modular marine, but its six to one, half dozen to the other. Tank is acrylic, 96”x36”x30” so by sizing convention a 450 .... holds 400 gallons before displacement. Made by fishtanksdirect. I’ve been very happy with it. Here’s the rear overflow box.

 

[dreamcatcherr9]

EMS would be a good choice. I went with the 32” modular marine, but its six to one, half dozen to the other. Tank is acrylic, 96”x36”x30” so by sizing convention a 450 .... holds 400 gallons before displacement. Made by fishtanksdirect. I’ve been very happy with it. Here’s the rear overflow box.

Ok, forgive the nosy questions. 3 returns, 5 drains?

I see 1 pvc clamped to stand. One is clamped to tank (?). How did you accomplish that? Super strong Double sided tape?

 

[ca1ore]

No worries. I had MM customize the overflow for me to have five drains. Three are siphons, then a secondary and an emergency. I run a basement sump room so wanted to put gravity to good use. Each siphon feeds something specifically. Those other three pipes are a closed loop. Clamp was just resting there, not actually attached. Check out my build thread if you want to see the ‘journey’.

Monster Build - Simon's 450

About to switch from my current 265 to a 450. Here is progress so far (2 months work in pictures).

www.reef2reef.com

 

[dreamcatcherr9]

No worries. I had MM customize the overflow for me to have five drains. Three are s

That’s awesome. 3 safety back ups! Expect the extra plumbing work, that’s smart.

 

[RobB'z Reef]

EMS would be a good choice. I went with the 32” modular marine, but its six to one, half dozen to the other. Tank is acrylic, 96”x36”x30” so by sizing convention a 450 .... holds 400 gallons before displacement. Made by fishtanksdirect. I’ve been very happy with it. Here’s the rear overflow box.

nice setup... @ca1ore! I'm looking at using a modular marine 3,000 gph unit. How far from the top of the tank is your water level in that configuration? I'm new to these overflows and wondered how you calculate the hole location based on where you want your water level to be.

thanks!

 

[ca1ore]

I just told the tank builder I wanted 1/2” of clearance between the bottom of the braces and the top of the overflow .... ostensibly so I could get the cover in and out. Proved to be such a pain that I don’t actually use the cover anymore. Since I was making my own top trim, I did not need to be all that precise. If you have trim, my rule of thumb is to have the bottom of the tooth slots no lower than the bottom edge of the trim.

 

[jstncoffman]

just curious as too what type of drain are you considering
Herbie
Durso
Bean animal?
I personally use external overflow boxs with herbie style " super quiet and flow is really good, eshopps sells the overflows with everything ready to install including the glass drill bits

 

[RobB'z Reef]

I just told the tank builder I wanted 1/2” of clearance between the bottom of the braces and the top of the overflow .... ostensibly so I could get the cover in and out. Proved to be such a pain that I don’t actually use the cover anymore. Since I was making my own top trim, I did not need to be all that precise. If you have trim, my rule of thumb is to have the bottom of the tooth slots no lower than the bottom edge of the trim.

Thanks! It'll be a euro braced glass tank.