# my DIY PVC overflow, 1.5"



## jwal (Jan 17, 2008)

Hi, DIYers :fish:

I hope I didn't do anything stupid with this overflow. Anyone see anything wrong? I copied some of the others I've found on the forum.

I was thinking about gluing some 1.5" flexible PVC to the ball valve and running that to my DIY sump (not done with that).

i can't test this for a while because I'm still saving up for a 125/135 gallon tank


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## under_control (Jan 9, 2008)

attach a barbed end to the ball valve if you are going to run hose to the sump. From what I'm seeing it looks like it should work.


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## jwal (Jan 17, 2008)

what about the "flexible PVC" that uses regular PVC glue? anyone know if that's any good?

I saw some barbs at home depot but I didn't see any 1.5" elbow barbs ... or maybe I could get the 1.5" ribbed pool hose, i just wasnt sure how you attach that to the pvc


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## a_c_arnold (Mar 7, 2008)

Maybe I'm missing something, but won't the air inlet on your overflow break the syphon.


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## jwal (Jan 17, 2008)

maybe an expert could chime in, but I believe the point of the air inlet is to break the siphon (because if it siphoned all the way down it would drain water too fast). Since the "Wye" fitting is above the lowest part of the U on the inside of the tank then I believe it should maintain a siphon in that part of the unit


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## bulldogg7 (Mar 3, 2003)

I'm curious, haven't tried one yet, Love the pictures :thumb: What's the ball valve for? If you slow it down, you'll flood the tank. Just for "maintenance" reasons? Looks like it should work fine.


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## jwal (Jan 17, 2008)

well, i dunno what the ball valve is for  I figured it would be nice to stop the water flow without breaking the siphon? if not, then I wasted $10 :lol:

i can't wait to try this thing out


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## bulldogg7 (Mar 3, 2003)

If you don't have the air inlet side, it will draw air out the other end, along with all the water in the pipes. The middle portion will stay full of water this way, when the water spills in the intake side the level in the pipes will rise and just spill over the "Wye'd" pipe into the sump.


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## bulldogg7 (Mar 3, 2003)

> then I wasted $10


No, nice addition. I just wouldn't stop the flow with the pump turned on  
Looks like it should keep the "siphon" by itself, safe in a power outage. Can't wait to see how it works out.


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## jwal (Jan 17, 2008)

yeah, you're right, that would make the water start rising rapidly in the tank 

but, i think it would be nice for changing out filter pads? i don't know, i've never had any of this stuff before 

so, flip the power on the pump off, and then immediately turn the ball valve or something? then ...don't forget to open it before you turn the pump back on of course


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## bulldogg7 (Mar 3, 2003)

You shouldn't even need to touch the ball-valve. The center portion should always be full of water.









Once the level inside the pipes drops to the Wye it will stop going into the sump. Once the level in the tank drops below the inlet pipe, no more water is added and it will also stop going to the sump.


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## jwal (Jan 17, 2008)

oh, yeah, i just realized that a second ago. your colored in drawing confirms my moment of enlightenment. i just thought about how it works and now it all makes perfect sense. so basically the ball valve is pretty useless


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## jwal (Jan 17, 2008)

although maybe the ball valve could help make priming the siphon a lot easier...less air to suck out


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## jwal (Jan 17, 2008)

ok new questions...didn't really want to start a new topic because it relates to this

should I get a Mag Drive 12 (1200 GPH) or Mag Drive 18 (1800 GPH)? 
with a 5' head height and 2 elbows and/or a spray bar (haven't figured that part out yet), what do you think the flow rate would be then and could this theoretically handle it? :-?

oh and tank size will be 125 or 135


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## Craigthor (Jan 9, 2007)

don't forget an air check valve in the loop going over the tank. If you don't get all the air out you run the risk of it losing siphon once the power is cut. monsterfishkeepers.com in the diy section has some 60 pages on building DIY overflows and different mods.

Craig


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## bulldogg7 (Mar 3, 2003)

There was a link posted here that told how much flow you could get from different diameter standpipes, I can't find it :-? 
Just go to MFK and type pvc overflow in the search box, hundreds of results come up :thumb: 
I'm still looking...


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## bulldogg7 (Mar 3, 2003)

http://www.reefcentral.com/calc/drain.php
http://www.reefcentral.com/calc/hlc2.php
FINALLY googled it up.

They've got some diy's there too, but it's a saltwater site.


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## jwal (Jan 17, 2008)

yep, i added the checkvalve in. i think i'll attach it to a powerhead venturi to keep air bubbles out. will post some more pics whenever i get it running on the tank 

i'm not sure what that drain calculator applies to? I think it applies to standard overflows and I'm betting these siphon types are somewhat less due to the number of elbows leading to more water resistance.


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## chefkeith (Sep 25, 2004)

A check valve will malfunction eventually when used with a powerhead venturi. You only want air passing through the check valve. With a powerhead venturi, water will pass through the check valve and it will eventually get clogged. Then when air does build up in the overflow, the siphon breaks, the tank overflows, and someone will be mopping the floor. Believe me, I've tried it.

The powerhead venturi idea does work great without using a check valve. Just remove the check valve and fit the airline tubing right into that hole. You may have to open up the hole a little bit though. That's pretty much what I did and I haven't had any problems since.


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## jwal (Jan 17, 2008)

hmm, didn't think about that. I guess it's because the checkvalve has a tiny opening.
I don't understand how you get the airline tubing to stay in the hole ? friction fit?

What about using a check valve and one of those "aqua lifter" pumps instead?


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## chefkeith (Sep 25, 2004)

Just squeeze the airline tubing in the hole. It should hold pretty well. It nothing that plumbers epoxy can't fix if you drill the hole too big.

An aqualifter will work the same way as a venturi on a powerhead. An aqualifter will save you a few dollars though. A check valve will still get clogged if water is passing through it.


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## bulldogg7 (Mar 3, 2003)

with an aqua lifter I don't think you would need a check valve, but even if it failed the aqualifter would still suck on it, so no harm done unless it completely clogged up. The aqua lifter would be better if you can get one.


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## schmecky (Jun 28, 2003)

regarding your pump sizing:

One thing I was thinking when I rebuild my system (Have had my main aquarium dismantled since I moved - remodling the house, then I'm going to build a new Sump/Wet-Dry)

I think I'll do a 2 pump combo-

My 135g aquarium was served just fine for years by the Mag 12, but when I rebuild I'm thinking of adding a Mag 7 or 9.5 for redundancy. It shouldn't add so much additional flow that my overflows wouldn't handle the extra flowage, but this way if my Mag 12 ever burns out (while I'm on a vacation or something) the bacteria colony won't die, and it should provide enough filtration to not stress the fish.


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## archon (Aug 20, 2003)

A couple of questions on the original picture.

1) How does one prime this thing?

2) Is PVC cement/primer bad for fish. I only see purple primer on the PVC where it will be outside of the tank. Are the fittings inside the tank just hand tight?


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## stslimited84 (Oct 5, 2007)

chefkeith said:


> A check valve will malfunction eventually when used with a powerhead venturi. You only want air passing through the check valve. With a powerhead venturi, water will pass through the check valve and it will eventually get clogged. Then when air does build up in the overflow, the siphon breaks, the tank overflows, and someone will be mopping the floor. Believe me, I've tried it.
> 
> The powerhead venturi idea does work great without using a check valve. Just remove the check valve and fit the airline tubing right into that hole. You may have to open up the hole a little bit though. That's pretty much what I did and I haven't had any problems since.


After fitting the airline tubing into the hole, should you silicone around the tubing to make the hole watertight?

I'm going to start building my overflows soon. Thanks!


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## herb (Mar 23, 2003)

the only thing i can say you MAY want to add to your overflow is a cap on the outside pipe, above the wye, with a small hole in it, this will stop the gurgling noise that you may experience, the hole will need to start out small and slowly increase it. this is called a modified durso, you can research this if you like. the hole silences the gurgling noise and when pump is shut down allows the u-bend to keep its water.

herb


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## jwal (Jan 17, 2008)

archon said:


> A couple of questions on the original picture.
> 
> 1) How does one prime this thing?
> 
> 2) Is PVC cement/primer bad for fish. I only see purple primer on the PVC where it will be outside of the tank. Are the fittings inside the tank just hand tight?


to prime, you pour water in both sides, then suck out the air from the very top of the (upside down) U bend.The photos don't show it, but now I have drilled a hole at the top and inserted 1/8" airline tubing. you need to remove air bubbles during operation because small air bubbles will build up every few days.

I don't think there is anything harmful in the PVC primer and cement after it has dried. I only left this off on the inside in case I need to modify the water level and/or rotate the pipes. On my inside connections I wrapped the PVC with a few rounds of plumber's tape just for a tighter fit.


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## jwal (Jan 17, 2008)

herb said:


> the only thing i can say you MAY want to add to your overflow is a cap on the outside pipe, above the wye, with a small hole in it, this will stop the gurgling noise that you may experience, the hole will need to start out small and slowly increase it. this is called a modified durso, you can research this if you like. the hole silences the gurgling noise and when pump is shut down allows the u-bend to keep its water.
> 
> herb


i might try that. i also saw someone that just stuffed a big wad of polyester batting in there to reduce noise and not block airflow.


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## stslimited84 (Oct 5, 2007)

I think there are problems that arise when you put an end cap on there. If you read through the almost 70 some pages of threads at monster fish keepers forums. The cap seems to cause more problems then its worth.

They have several solutions in the threads


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## mel_cp6 (Feb 3, 2009)

hows the flow on your 1.5" overflow. im thinking of upgrading to that size 
since my 1" cant keep up with my pump that is capable of pumping 780 at 0 headheigth and about 600 at 5ft.

i know this this thread is old but it worth a shot.


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## jwal (Jan 17, 2008)

i actually havent been able to test out the flow rate yet. i got a tank with pre-drilled standing pipe overflow so i unfortunately didn't get to use the overflow. I could probably test it in the bathtub but i'm not sure how accurate that would be


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## jwal (Jan 17, 2008)

I wanted to bump the thread because I actually put this overflow to use and it works fine.

A couple notes:
- It's a good idea to use a check valve (at the top where it hangs on the tank) to remove air bubbles in the siphon area. Attach an aqua-lifter pump to remove bubbles for continuous reliable operation
- I added a screen mesh pre-filter, wrapped around the top of the pipe and attached with rubber bands to prevent large debris from clogging the drain.
- To reduce noise (gurgling and burping), you can hang a short section of airline tubing inside the in-tank skimmer part (where the water enters the first pipe). If you play around with the length and position, the gurgling will almost go away completely.

I believe this 1.5" pvc overflow can handle over 1000 gph. It seems to handle about 750 gph with room to spare.


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## parkayandbutter (Jan 15, 2008)

NOISY SUCker that will be........... Good luck trying to survive it


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## jwal (Jan 17, 2008)

Here is a prefilter idea that I adapted, and I think it works great. This plastic grid is sold in hobby/craft stores for cheap.


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## AfricanMike (Dec 15, 2006)

Since this bad boy is up and running on your tank, mind taking a few pictures of the set-up and posting them?


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