DIY Alternative Overflow Box

[MadTownMax]

Ahhh- I see, you basically made it like the Life-reef HOB overflows, but with PVC pipe - nice idea!

[WarEagleNR88]

Originally posted by pioneerlog
any reason this wouldnt work for a larger tank? Say a 55....thinking about using 3" sch20 & 1" over the tank..
Geoff

Like I said before, the limiting factor is the size of the exit tube. Just as with CPR overflows, there is an increase in overflow capacity with an increase in bulkhead size. This makes perfect since the larger the hole the more water you can put down it. But the question comes to how much does it increase? As for this I'm not exactly sure.

On Marine Depot, they mention that a 1" bulkhead with a 10" wide overflow section can handle 800 gph. So you would think that a 0.5" bulkhead would handle 400 gph, right? Well then it goes on to say that 2x1" overflows with the same 10" overflow can handle 1200 gph. So, there seems to be some screwy calculations with what they tell, so it's hard to say. Best method is to be your own design engineer and test and check.

So, what's the size of the tank and how much water do you want to go down the overflow? Personally, I think I would assume maybe 200 max gph for a 0.5" pipe, 400 max gph for a 0.75" pipe, 600 max gph for a 1", 800 max gph for a 1.25" pipe, 1000 max gph for a 1.5" just to be on the safe side. I'd assume these unless someone actually tests them all out.

[WarEagleNR88]

Oh and those figures from Marine Depot are for their CPR Overflows just to clarify.

[crrichey]

The reason this occurs is that when it comes to the diameter of plumbing, what you would consider to be doubled isn't always true. It has to due with circles and volume and some other geometric terms that I am not familiar with. I heard it on another thread here on RC a little while ago, don't remember the exact post though.

[melev]

What Cody is referring to is the surface area of the pipe. The formula is Pi(radius₂).

with .5" pipe, it is 3.1416 x (.25 x .25) = .20"
with 1" pipe, it is 3.1416 x (.5 x .5) = .76"
with 1.5" pipe, it is 3.1416 x (.75 x .75) = 1.77"
with 2" pipe, it is 3.1416 x (1 x 1) = 3.14"

As you can see the surface area or space the water has to travel through is much different between .5" and 2", but not 4 times as much right? It is actually almost 16 times as much.

[crrichey]

Thank you, exatly what I was trying to say, lol!

[crrichey]

Using that formula, how would you determine how much water a pipe could handle per hour?

[WarEagleNR88]

Originally posted by ChinChek787
Using that formula, how would you determine how much water a pipe could handle per hour?

Ah good call Melev, I wasn't even thinking about the cross sectional area!

How much water you can put through a pipe all depends on how much that water is pressurized. I'd imagine you could pressurize water until your pipes explode! Sched40 is like 450psi or so? I know underpressurizing water vaporizes it. I think pure water at sea level vaporizes at around 100 deg F if it is in a 1psi environment. Yup, I looked in my old thermal systems engineering book and the highest pressure they have recorded for water on its pressure table is 3203.6 psi. Water at that pressure vaporizes at 705.4 deg F it says. So... how fast the water can go is dependent on the strength of the pipes.

I think to figure this out we'd have to turn to volumetric flow rate to find how quickly a pipe can process water. The equation is Q = AV where Q is the volumetric flow rate, V is the velocity of the water (ft/sec) and A is the cross sectional area of the ID of the pipe (ft2). Since we typically measure distances in the english system in feet and water in gallons, you have to change gallons to feet cubed (*0.13368) and then hours to seconds (/3600) so the equations work out. So when you see gallons per hour, that's actually a modified Q. Doing some quick math on a 1200 gph rated pump at 0 head and no losses through a 1" pipe gives a velocity of ~8.17 ft/sec.

I actually measured my flow rate earlier today on my 1/2" overflow. Mind you though that there is a lot of back pressure on the display overflow, and I have to fine tune it to keep the display from spilling on the floor. My wife timed while I filled up a 22 oz glass from where it empties into my sump. It took 10 seconds to fill so 132 oz/min and ~62 gph. And since the flow is turned way down, it's not even functioning at maxium capacity. Doing the above calcs for velocity gives ~1.7 ft/sec through the 0.5" pipe.

If I increase that to 200 gph (my previous stated max volumetric flow rate), then I'm looking at ~5.4 ft/sec. I'm going out on a limb here, but 10 ft/sec would probably be the highest you'd want to go. Not because higher is unachievable, but because at that speed you get hammer effect. Do a quick google if you've questions about hammer effect. Basically it's a shockwave created by the inertia of a quickly stopped uncompressible liquid. This "rule" is around so pipes should be rated the correct size or valves and other things can break in a plumbing system. All that said:

0.50", 367.2 gph
0.75", 826.2 gph
1.00", 1468.8 gph
1.25", 2295.0 gph
1.50", 3304.8 gph

Please feel free to comment.

- WarEagle

[WarEagleNR88]

And just remember that those values are for maximum flow with no head or restrictions. Or the first time you try to put 1450 gph through a 1" bulkhead, all things considered you're going to dump water on the floor. I almost guarantee it.

[crrichey]

My comment, the values would have been enough for me

[aggie03]

Im thinking of building one of these overflows, for my twenty nine should i go with the 1/2 inch or one inch? Id like to be able to have a pretty good flow on my return so i was thinking one inch any thoughts?

[sjm817]

600 GPH through a 1" drain pipe (gravity) is a pretty well accepted value.

[cloudancer]

I can vouch for this working. I ran one like it (without the ball valve) for about 9 months on our freshwater planted tank. Eventually took it down because we couldn't keep the intake from clogging.

[Synergy]

WarEagleNR88, so how much flow do you think your design as built handles?

Also how far into the tank does it stick. I am thinking about building one for a 5 gal tank I have.

Thanks,
Chris

[aggie03]

Well i broke down and tried to build this thing out of 1 inch, i felt like i got all the air out through the standpipe but i cant get it to siphon. Any ideas?

[Rivalpc]

1 inch was a pain to start; i built one to test the dimensions needed. Assuming you have the right diminsions for lengths to create the proper pressure to restart the siphon. I found that you need to close the ball valve, poor water into the rear stand pipe, which needed to be taller than the tank max height, to get pipes full. then suck the air out while filling the rear pipe until it starts to fill the overflow section. Imagine how a toilet works.

Just to give you an idea of what was actually needed for initial suction to get it flowing for me was to use a small shop vac with a closed ball valve while my wife fills the overflow, once you get flow up the rear standpipe open the valve. at first it sounded like a giant bong but started to flow good. The only problem i had was the water wouldnt flow once I shut off the intake flow then restarted to simulate a power outage.
Seems my intake isnt far enough under water to created the needed pressure. So far its turning our to be a least 12 inches deep inside the tank.

maybe if convince WarEagleNR88 to give us some dimension on his unit we could get a better "scale" for 1 inch setups.

[horkn]

i can say i am really interested, esp in a 1" setup.


i want so badly to put a fuge on my 35g, and this seems the cheapest good way to do it.

[aggie03]

I agree but i cant seem to figure out the right dimensions to maintain the siphon. I guess i cant get enough pressure from the tank side?

[WarEagleNR88]

Originally posted by WarEagleNR88
Problems:
The hardest part of the whole thing was getting it initially primed. This proved to require some coordination on my part of closing the ball valve, draining the refugium below its overflow, turning on the inflow/feed from the display overflow, rushing over to the refugium, and sucking on stand pipe to fill pressure section with water. Then as the refugium overflow was full submerged, ball valve on gravity section would be opened fully and proper draining of refugium would commence. Solutions to this problem might be to 1) drill a small hole in the top of the over-the-tank/pressure portion, Tap it, put on a nipple/barb&airline and suck air out of the pressure section, turn off and then commence proper gravity draining. 2) let gravity pull the water at the bottom of the pressure section to prime the pressure section with water by draining the tank, install a tee and a ball valve there with hardline/barb&vinyl, suck on bottom of vinyl into bucket or sump, close ball valve when sure all air is out of pressure section. Rotate 2nd ball valve on gravity section and and open inflow/feed from the display overflow.

Guys I've already told you how to make this work easier. Getting the thing primed initially is very tough! Just the other day I made it lose suction on purpose--close the ball valve and blow out the water back into the tank. Suction lost. Then I restarted it. Again it was difficult. But here are some other suggestions than the ones above that will hopefully get yours primed and working correctly. Note that I haven't done any modifications to mine, it still looks like the one in the picture.

1) This is the hard part and how I got it working. Fill tank to where the water level is as far above the level of the overflow as possible--dont overflow your tank! Put your mouth on the stand pipe, suck water until it gets to your mouth. If it goes in your mouth, dont swallow just spit it out. This is important! Repeat this a couple of times until you feel you've fully primed the system. Twist the ball valve open and water should begin to drain. Help it along by slightly blowing into the stand pipe--increasing the air pressure--until you can easily blow into it. It should be hard to blow at first but will get really easy at one point. This is because you're blowing against the tank pressure and your air is going into the exit pipe. Very important that you don't blow too hard because you could push your air into the over-the-tank section. Hopefully your tank will begin to drain a little. Keep trying to suck air out of the system by sucking on the stand pipe and alternating between blowing on it to increase air pressure. Eventually after some hassle you should have it primed and draining properly. I'd go swish some fresh water to get the taste out of your mouth. Be very careful not to let any water down your throat--think of it as your siphoning gas. Just remember to use extreme caution, especially if you keep highly toxic corals.

2) This way will be much safer. Depending on if you have room or not, you can submerge the whole thing and turn it upside down and right side up underwater and this will most definitely get it primed as it will release all the air and it will fill with water. Then put it back on the tank with water in it--some will spill out--fasten everything back up, and as soon as you twist the ball valve it should start going.

I hope these helps help those of you who are trying this out . If you can try the barb/tee on the over-the-tank part to pull air out of the place where you definitely need air out of, I recommend doing this. If you can't do that, try to turn the thing into a siphon drain by putting a tee and a ball valve at the very bottom of the outside over-the-tank section. Put on a barb and a vinyl tube onto the end of the ball valve (of course you'll need the right connections) with the end of the vinyl tube in your sump. You'll need to close your exit ball valve and temporarily cap your standpipe. Twist the ball valve open, suck on the end of the tube put it into your sump and it should easily drain water from your display. Twist the ball valve closed and open the exit ball valve. I'm pretty sure you should have exit flow. If those don't work, try the above two methods.

Any questions/clarification, please ask. And post pic of your setups, as we'd like to seem them. Maybe your design is not sufficient enough to get it to work. And remember, your mileage may vary on this DIY. After all it is DIY.

- WarEagle

[josh_peter]

For the top of the inlet (where you have the gutter guard) would it be easier just to get an end cap and drill some small holes in it? Like 1/8th. Then you would not have to try to trim down the gutter guard or glue it on to start with. Also, I think the end caps have a curve to them so with slits or holes it should prevent things from getting inside and also help muffle the drain sound.

[bob1965fish1]

hi


all you need to do is put a tee at the top and put a barbed fitting
and use a Aqua Lifter Pump that way you dont have suck on the pipe to start your overflow

[WarEagleNR88]

Yes I'd just like to mention that the tee at the top works very well. Put a tee at the top of the over-the-tank section with a ball valve. Suck on the ball valve until water gets to your mouth, close the ball valve and you'll have excellent flow. Although I haven't changed my original design--since it's working atm--I did retest using some spare PVC parts and it works really easy. So if you're having problems with getting proper suction, put a tee at the top of the over-the-tank section and you should have no problems getting it overflow correctly.

I will post more pictures soon of my attempts.

[daddypugg]

Couldn't you just put a removeable cap on the riser tube?

close the ball valve fill pipe and the siphon should auto start when the ball valve is open.

WarEagleNR88 I modified your image to help explain my thoughts (hope you don't mind).



I currently use a similar setup for my circulation pump on my water makeup can and it works very well.

[serhiyi]

Can you add some measurements to your picture?
I want to try it today with 1" pipe. What diameter and how deep intake should be?

[Manuel Martinez]

This is really an amazing trick. I can’t wait to do it, by my self this DIY. Congratulations WarEagleNR88.