FAQs about Overflow
Related Articles: Overflow Box Arrangements,
Systems by Bob Fenner, Myth of the One Inch Beast
(Why Relying on One Inch Overflows... or Overflow! Is
foolhardy) by Scott Vallembois, The Flowrates through various Bulkheads
(In relation to overflow drains)
Vallembois & Mike
Kirkman, Plumbing Return
Related FAQs: Overflows 1, Overflows 2, Overflows 3, & FAQs on: Rationale/Use, Sizing, Through-Hull Fittings, Hang-On Selection, Plumbing, Troubleshooting/Repair...
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Internal overflow leak 5/29/13
Hello aquatic experts,
I'm sure this question is answered somewhere on your site but it has
defeated my attempts to find it. I have a built in overflow that has a
small leak at the bottom. The leak is between the overflow and the tank
so no water gets on the floor as long as the power stays on. But since
the leak causes the overflow to equalize with the tank any power outage
will drain the tank about 6 inches, which is more than my sump can
<Have to get a larger sump (volume) and leave the water level down
I currently have the pump off, and closed the return valves so this can
not happen but I would like to get my tank connected to the sump again.
Is there a way I can seal this leak without draining the tank?
<A couple of standard approaches... there are epoxies... that can be
applied/reapplied around joints, with or w/o another piece of acrylic (I
take it as the material of construction... there are repairs for glass,
PVC...). All require draining the tank... You may want to consider
inserting an overflow pipe, pushed or threaded (if the
bulkhead/through-put fitting on your tank is threaded)... Raising
it/this to near the height/level of your overflow teeth>
Both the tank and the overflow are acrylic. The
overflow is in the middle if the back wall and goes from the base of the
tank up, with the holes in the bottom.
The leak is somewhere along the bottom edge where the overflow meets the
base but I do not know exactly where.
<Again... likely just thicker, more viscous (less fluid, more molasses
like) Weld-on is the route I'd go>
Thank you for your assistance.
<Take your time here... planning, containers, friends to help hand out
the gravel and rock... can be done in a few hours time with all tools
and materials on hand... Oh, and DO get the larger and/or additional
sump for transit volume, test (unplug pump/s) to assure it won't
overflow. Bob Fenner>
Coast to coast... Marineland system... actually DIY overflow
box design – 6/21/12
I have read and enjoy your books. I also enjoy your contributions to the
Reef Aquarium Hobby in general. However, I'm contacting you
in the hopes of acquiring the answers to a few questions concerning the
coast to coast overflow system. After two days of combing articles
and threads I can't seem to locate the answers on the web anywhere.
My questions concern this picture, they are below it. Please consider
taking a few minutes to respond.
<Okay... I see the attached>
I want to do the coast to coast on a 60" Marineland 120xh. I would
like to incorporate the C2C overflow Beanimal version with either a
closed loop manifold or manifold straight from the sump.
I am having a hard time discerning from the picture where the return
from the sump is entering this tank. ? Is it coming through
<I'd guess the return is hidden behind the top side (proximal in the
pic) faux wood aquarium frame... that it connects to the manifold
(discharge) PVC tees shown on the top right of the pic (front)>
Is the Bulkhead in the lower left corner feeding the manifold through
the black shielded line?
<It/this might be an auxiliary discharge... but could conceivably be an
alternate intake as well... I would cap and abandon it likely in both
Couldn't I just drill a hole at the central brace for a bulkhead and go
straight into the manifold rather than coming from a far end If this
were a true C2C/ wall2wall. What are the return line location
possibilities? Obviously, we can't return from the sump into the
<... please read here:
scroll down to "About Plumbing"... there are several possibilities to
explore here, and important that you be aware of pitfalls... in plumbing
Also, there are 2 open Bulkheads with screen protectors under the center
brace. Are these the drains for the manifold?
<Likely so... as well as the turned up elbows (white PVC) for intake>
Is it possible to put the drains for the manifold inside the overflow box
and not create issues with a Beanimal version of this overflow?
<Mmm, yes... but better to run through the back, overflow box area, as
shown in the BeanAnimal site:
Appreciate any insight,
Darrell in Carolina
<I'd read, study a bit more... Bob Fenner>
Overflow box and return pump/Plumbing 6/19/12
You guys are great.
You have helped me out a lot already as I try to plan my next tank.
I have a few questions dealing with the overflow box that I couldn't
find any answers to. The tank is going to be 72x36x28 acrylic with one
center trapezoid overflow box.
<Nice size tank.>
My first question is how long should the teeth be on the overflow box?
<Are you planning on making the overflow yourself? For what
manufacturers charge to include an overflow box with returns, it's not
worth the bother to DIY one. As to the length of the teeth, that
will depend on how high the top of the overflow is in relation to the
top of the aquarium. The number of teeth and the width of the
teeth also factor into this.>
I plan on having a Vortech or two in the tank so I don't know if that
makes a difference as far as waves or current?
<Shouldn't be in that size tank.>
Inside the overflow I will have two 1 1/2 inch Durso's and two 3/4 inch
returns running out each side of the trapezoid below the teeth. My
second question deals with the bulkhead choice. For the Durso's
can I use a slip fitting and just stick the Durso's in without gluing so
they can be removed for cleaning or should it be threaded?
<I would use the slip, should not cause any problems.>
How about underneath the tank leading to the sump, threaded or slip? Is
one way better than the other?
<I would definitely want a means to remove the drain plumbing from the
tank. You can use a slip providing you use a ball valve union
which should be used regardless of whether you use slip or threaded.>
I also have the same question about the two 3/4 returns. I will be using
flexible line inside the box to connect to the side wall bulkheads with
locline. My last question deals with the return pump. Have
you used or know anything about the super reef octopus water blaster
return pumps? I know you recommend Iwaki, but looking at different
forums these are
supposed to be quiet and use a lot less energy but I don't know about
<I've heard good reports on these pumps. May want to post this
question on one of the forums and get user comments.>
<You're welcome. James (Salty Dog)>
Re Overflow box and return pump/Plumbing 6/19/12
Thanks for the response. I am not making my own overflow but the
maker (James at Envision Acrylics) asked what size I wanted the teeth to
be so I wasn't sure what would be best?
<I would just ask for whatever the standard is. Too small a gap
between the teeth means more teeth are needed for a given flow and I
would not want the overflow box to be any bigger than necessary.>
With the bulkheads is slip or threaded preferred or it doesn't matter?
<I prefer the threaded.>
I see some that say to use threaded so if you have to move things or
change plumbing, you can, without replacing the bulkhead and others say
threaded will leak and you should only use slip fittings? What are
your thoughts on that?
<Threaded will not leak if installed properly. What I do is thread
a MPT to slip onto the bulkhead before I mount it. From there I
prefer slip and MPT true union ball valves. In the event you want
to change the plumbing you save your true union ball valve. Most
other their PVC plumbing is cheap so I'm not concerned with that.>
<You're welcome. James (Salty Dog)>
Internal overflow follow-up question 9/15/11
To follow up on the e-mail I sent earlier today regarding building my
internal overflow, it's also been recommended to me to use PVC
sheets for this purpose. Will they adhere to the walls using aquarium
Anyone used this method before with any measure of success?
<Silicone won't bond PVC; it will stick it, but will not make a
James (Salty Dog)>
structurally sound internal overflow 9/16/11
Howdy, gang, quick question this morning:
I'm building my internal overflow (corner bulkhead) out of scrap
acrylic for my 40g breeder...is there a method that is more
<Mmm, there are a few variations on a theme here; all sound>
What I mean is, does it matter if I were to use two pieces to
"square off" the overflow, if I were to use a single curved
piece to round off the corner (which for strict appearance sake, is my
favorite option). I figured it didn't really matter too much, but I
thought I'd check.
<Most folks form a square or rectangle... to accommodate the holes.
internal overflow assembly 9/28/11
I've been searching your site for internal overflow information for
the last hour or so, but have yet to find any information regarding my
In the process of setting up my drilled 40 gallon (1" bulkhead in
the rear right corner, bottom), I need to install an internal overflow
box. I would prefer to do one with "teeth"/slits rather than
just allowing it to flow over the top (I'm trying to keep snails
out of that chamber, though I suppose I could let it flow over and
attach some egg crate). This raised some questions of innovation, as
the tank is still bone dry on my living room floor.
1) If I went with an acrylic overflow, how would it adhere to the
<I'd use aquarium Silicone/Silastic... Will adhere well enough
to both surfaces to work here>
I've heard they may stick for a while, but will eventually have to
be re-sealed, and I'd prefer not to have to drain the tank
completely every couple of years to accomplish this.
<Not a worry, I assure you>
2) Scott V's article on 1" bulkheads scared the living
bejeebers out of me. Would a better idea be to drill another overflow
for a 1.5" in the other end, and work this one down for a return
<As in through the side? Mmm, well, the bigger the better... you
can/could always attach a tee... tee up the intake to raise the water
level relative to the through-hull>
I'd rather not run the return like this (was planning on keeping it
out of the tank except for the actual outlet).
<Then don't do it... or cut the 1.5" through the
3) Can an experienced LFS or glass shop cut "around" the
existing hole to expand it to one suitable for a 1.5"
<Yes; not hard to do. Write Mike at Glass-Holes.com re>
In the event of power failures, I am running the tank on a battery
back-up. In case of total pump failure, I am leaving room in the sump
to buffer this, as well as looking into different type of check
and installing a siphon break
on the return line.
As always, thanks for the sage advice.
<What re parsley and thyme?>
<And you. BobF>
re: internal overflow assembly 9/28/11
Thanks, Bob, as always, it's a pleasure to correspond with you.
<And you Dustin>
I don't have anything to add of significance, just that my
wife's name is Rosemary (since you decided to end with the S&G
<You will find... it will become live to your consciousness, that I
have very strong intuition>