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FAQs about Overflow Towers

Related Articles: Overflow Box Arrangements, Plumbing Marine 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) by Scott Vallembois & Mike Kirkman, Plumbing Return Manifolds, Refugiums

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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 handle.
<Have to get a larger sump (volume) and leave the water level down there...>
  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.
<All right>
I am having a hard time discerning from the picture where the return from the sump is entering this tank. ?   Is it coming through the manifold?
<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 cases>
 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 overflow box.
<... please read here: http://www.wetwebmedia.com/marsetupindex2.htm
scroll down to "About Plumbing"... there are several possibilities to explore here, and important that you be aware of pitfalls... in plumbing location, sizing...>
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
<Hi Kevin>
You guys are great.
<Thank you.>
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 durability etc.
<I've heard good reports on these pumps.  May want to post this question on one of the forums and get user comments.>
Thanks again.
<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
<Hello Dustin>
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 silicone?
Anyone used this method before with any measure of success?
<Silicone won't bond PVC; it will stick it, but will not make a complete bond.
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 structurally sound?
<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. Bob Fenner>

internal overflow assembly   9/28/11
Greetings, Crew.
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 query.
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 glass?
<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 pipe?
<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 bottom...>
3) Can an experienced LFS or glass shop cut "around" the existing hole to expand it to one suitable for a 1.5" bulkhead?
<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 valves
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 joke).
<You will find... it will become live to your consciousness, that I have very strong intuition>

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