# Skimmerless PVC Overflow troubles



## driscoll8541 (Oct 25, 2010)

I built this overflow out of 1.25 PVC, hooked a 560gph pond pump from Lowes on the return, and i have to turn the pump down half way for the overflow to keep up. I just ordered my aqualifter, but I thought i could get it going by using one of those one way air valves and priming it manually, i also tried hooking it up to my powerhead but that doesnt do anything. I was wondering why 1.25 pvc couldnt keep up with the full pump. I'm probably gonna build another one that skims from surface and use them both, (2) 1.25 pvc overflows for a 560 gph pump, that seems wrong?

I tried to add pics, not sure if it worked

http://www.aquariumlife.net/projects/diy-overflow/120.asp


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## kev416 (Aug 22, 2010)

It's a vertical hole for discharging into the drain line. The rate is limited by the yellow tee/green elbow. In order to have it be full out you have to ride the water level in the tank above this vertical discharge. Which means the inside water level in the tank will be much higher than the tee/elbow. You would have to have a very large sump to take the excess water in the event of a power failure. The vertical hole (1-1/4") will best function half way where the water level is flowing spilling over through the 1-1/4" vertical hole which means a lot less than an open bore of 1-1/4". Does this make sense? In this design what stops a fish from entering the siphon tube? You have a screen on it? The benefit of a overflow box is to clear the surface water for gas exchange. Without a skimbox you won't accomplish this.


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## kev416 (Aug 22, 2010)

Also check there's absolutely no air in the blue utube. Did you glue the red elbow in place? I can see purple primer which leads me to believe you did. The original designer suggests you leave it unglued so you can turn it up and fill the middle chamber. Any trapped air in the blue utube would be difficult to clear with the length of the drop in the middle chamber and air will slow the flow. 

It could probably do 560gph but it would be dangerously close to overfilling your tank.


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## waj8 (Jun 30, 2010)

This design kind of mystifies me. As far as I can tell it is not really so much an overflow as a siphon. You can get into a lot of trouble with something like this. There is nothing controlling the the water level in the main tank. If the water in the tank falls too far, the siphon will break. The outflow pipe is too small. The whole thing is a closed system so if water stop flowing the siphon will break. You would need a trap and a vent or some kind of container on the outflow. You would need a giant sump in the event of a power failure and once the pump restarts since the siphon broke the tank would overflow. Maybe I am not understanding the design.

I like the concept of the multiple overflow tubes though. I might steal that idea for myself. If you add a trap and a vent on the outflow and some sort of container on the tank side for water to flow into and increase the size of the outflow to 1" the thing could be viable.


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## kev416 (Aug 22, 2010)

*PVC overflow*

Sometimes you can go overboard with designs...


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## driscoll8541 (Oct 25, 2010)

thanks for the replies guys!

Kev, i did get lost half way through your first post. And i sure did glue that red elbow, I was so busy worrying about everything being uniform i forgot. Then I almost did it again when I made the 2nd overflow that skims, I primed it but didnt glue it, which is still a pain in the butt cause it doesnt turn easy now. 

I'm pretty sure i got the air out of the blue tube cause I sucked on it until water was coming up the airline tube, then i hooked it up to the powerhead without letting any air in, They say the powerhead is supposed to pull air out of there, but mine dont, it just doesnt let air in. I ordered a aqua lifter, it should be here soon.

If the power goes out they say i should be ok, as long as the sump can hold the low water line in the fish tank and the return from the pump doesnt back siphon when it shuts off. The water stays in the pipe and when the power starts again the aqualifter will prime the blue tube and everything should continue. Even though there is a siphon in the blue tube, the drain to the sump is just oveflowing out of the T. If water isnt pumped into the tank the drain will stop even though the intake is low in the fish tank. 

The sump is a 55 gal, 3/4 full cause im gonna water some growbeds out of there. Im gonna set-up a aquaponics system. Im trying to decide on either Koi or tilapia. Im gonna put it on youtube, ill put a link here. Thanks again.

This is what my face would look like if i walked into a flooded bedroom, starting from before i open the door.


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## kev416 (Aug 22, 2010)

Ya, I thought I lost ya. LOL A vertical hole is a side discharge overflow. They are rare although Chico from Aquariama use to make a lot. They are used primarily for low tanks close to the ground where you need to flow into a sump at a certain height. A conventional overflow has a horizontal hole at the bottom of the outside box. Both have to allow air through them as they drain. However, your design can ride a lot higher and push the water level up without the skimbox.

You can use a scrubbing pad or some 400 grit emery cloth to sand down that primed elbow. You can use water as you sand it. Should make it easier to twist.


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## driscoll8541 (Oct 25, 2010)

Well do, thanks for the help. I'll post a video of testing once some silicon cures.


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## hermitcrab (Sep 7, 2010)

*This design produce not much flow*

This design produce not much flow, this is a better design for much better flow


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## driscoll8541 (Oct 25, 2010)

Thanks, Do you think i can have the intake at the bottom of the fish tank?


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## gucci17 (Oct 11, 2007)

driscoll8541 said:


> Thanks, Do you think i can have the intake at the bottom of the fish tank?


To me it doesn't make sense to have the intake on the bottom of the tank because you are supposed to be surface skimming. With the intake on the bottom, you will suck the tank dry in the event of a power failure.


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## driscoll8541 (Oct 25, 2010)

gucci17 said:


> To me it doesn't make sense to have the intake on the bottom of the tank because you are supposed to be surface skimming. With the intake on the bottom, you will suck the tank dry in the event of a power failure.


The siphon stops when the power is out, thats the beauty of it. And it makes alot of since because fish crap sinks.


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## gucci17 (Oct 11, 2007)

driscoll8541 said:


> The siphon stops when the power is out, thats the beauty of it. And it makes alot of since because fish crap sinks.


Not quite sure how you have your plumbing setup.

Did you drill a hole at the top to stop the syphon? If so, what do you have to start the syphon again after power failure?


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## driscoll8541 (Oct 25, 2010)

Im gonna have a aqualifter pump to pull air out, but that is just for safety. I manually pulled the air out then threw the airline in the tank and when the power shuts off the water level only goes down to the outside T. Then when the power is restored the siphon restarts by itself with no aqua lifter. The aqualifter was supposed to arrive today, i was looking for my order confirm about it when i noticed your post. 
I've got two overflows now, one that skims and one that intakes low. Cause the 1st one could not keep up with the pump im using. Luckily all that pvc pipe dont bother me because it is just a holding tank for a aquaponics system. If i was to do it again i would use Hermit crabs design, but i want a low intake to remove solids. Im not too mad cause having both is nice.


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## gucci17 (Oct 11, 2007)

driscoll8541 said:


> Im gonna have a aqualifter pump to pull air out, but that is just for safety. I manually pulled the air out then threw the airline in the tank and when the power shuts off the water level only goes down to the outside T. Then when the power is restored the siphon restarts by itself with no aqua lifter. The aqualifter was supposed to arrive today, i was looking for my order confirm about it when i noticed your post.
> I've got two overflows now, one that skims and one that intakes low. Cause the 1st one could not keep up with the pump im using. Luckily all that pvc pipe dont bother me because it is just a holding tank for a aquaponics system. If i was to do it again i would use Hermit crabs design, but i want a low intake to remove solids. Im not too mad cause having both is nice.


That's new...a different style of herbie kinda. I see how it could stop at the outside T but for it to start up again without the assistance of an aqualifter is what I don't understand.

Sorry, it's new to me so I'm just curious how exactly it works.


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## driscoll8541 (Oct 25, 2010)

Water stays inside the pipe kinda like it does in a cup when you pull it out of water upsidedown. Once you prime the overflow,either skimmer or not, the water remains in the pipe. the aqualifter just pulls air out of the pipe that might get in there during operation(bubbles) and it pulls out the gases made by the bacteria growing in there.


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## bigfishy (Jun 19, 2009)

driscoll8541 said:


> Water stays inside the pipe kinda like it does in a cup when you pull it out of water upsidedown. Once you prime the overflow,either skimmer or not, the water remains in the pipe. the aqualifter just pulls air out of the pipe that might get in there during operation(bubbles) and it pulls out the gases made by the bacteria growing in there.


This is what drisco's tank should looks like when he is done with the overflow

tubey style (a picture is better than a thousand words)

This is not my tank, and this person (I forgot his name) lives in Mississauga too


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## driscoll8541 (Oct 25, 2010)

That looks pretty good!


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## kev416 (Aug 22, 2010)

driscoll8541 said:


> Thanks, Do you think i can have the intake at the bottom of the fish tank?


You have to have the surface skimming siphon tubes. Notice where the tee is. If you drained from the bottom it would fall to this level and drain the 1/2 the tank in the diagram shown.

On another point concerning your design... You could do away with the aqualifter but you have to push enough water thru the wet utube to void air bubbles. If you designed it with 1" wet tube and 1-1/2 for the remained it would work without the need of an aqualifter. The reason overflows use an aqualifter is in the design of the acrylic units like a CPR. The intergral utube is more like a uchannel. Because of this... it slows the flow down and air bubbles become trapped in it. The aqualifter is used to avoid any air. You could also accomplish this by sucking the air out weekly if you had a CPR. But a round utube should be able to void air as long as it's sized correctly to the flow. But since you built it already the aqualifter should work.

I take it that when the power goes off with both your first design and the new skimmer design the water still falls to the old level at the tee of the bottom siphoning unit.


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## driscoll8541 (Oct 25, 2010)

Yep, when the power goes he water level falls to the ext. T of the low intake overflow. i got my aqualifter now so im up and runnin. Im gonna go try to make a video right now. My youtube name is daniel3484.


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## kev416 (Aug 22, 2010)

utube on you tube... 

I think tilapia tastes better than goldfish. Then again I've never eaten goldfish. Sustainable food production... eat what you keep. Come on bigfishy fry up that datnoid!


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## driscoll8541 (Oct 25, 2010)

did you see my vid? let me know what you think.


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## kev416 (Aug 22, 2010)

Yup. Nice. Is that light the one home depot sells for about a hundred bucks? Eight T8s? Is the grow bed made from under the bed containers painted black? Was wondering if the light fits on the wire rack or is it a bit too big?


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## driscoll8541 (Oct 25, 2010)

No the light is from a hydro store, 4 x t5's, i got 2 of them on craigslist. The lights fit perfect on the stand, they are both 4ft. Yes those growbeds are underthebed containers painted black. Typically you want your growbeds atleast 8" deep, but i didnt know that when i made them. Im gonna add some deeper ones when my tilapia get bigger. My tilapia should be here in acouple weeks. And no the goldfish are not for eating, somehow they survive my warmouth bass so i put them in my other pond with my koi.


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## kev416 (Aug 22, 2010)

Did you buy the 'hybrid food fish' tilapia or the aquarium trade buttikoferi or mariae? Looks great. Thanks. I'm thinking about trying a aquaponics set up myself.


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## driscoll8541 (Oct 25, 2010)

This is my fav aquaponic site and the other is where i ordered my fish from. That link should take you directly to the blue tilapia. If you do try it out, treat your room like a lab, keep it clean, and start from seeds so you dont get any bugs on your plants.

http://aquaponicscommunity.com/

http://tilapiasource.com/zc/blue-tilapia?zenid=e32cdad6275697f850e12757a078a8e8


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## kev416 (Aug 22, 2010)

Thanks for the links!


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## hermitcrab (Sep 7, 2010)

*water flow*

pointing downward and using T tube like yours = water pulled by gravity, free falling >>slow flow

pointing upward = water pulled by water pressure (all water volume higher than tube) >>faster flow


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## kev416 (Aug 22, 2010)

hermitcrab said:


> pointing downward and using T tube like yours = water pulled by gravity, free falling >>slow flow
> 
> pointing upward = water pulled by water pressure (all water volume higher than tube) >>faster flow


The location of the tee going to the sump is the reason yours flows much faster. Yours is about 4" lower. Driscoll's will always drop to the level of the tee (without surface skimming) but his sump is large enough to take the water volume. Even if he decided to use additional utubes to surface skim it will still flow at the same rate because the tee is set as high as it is. The potential airlock would be greater because of this. It's better left as is to bottom siphon.


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## driscoll8541 (Oct 25, 2010)

kev416 said:


> The location of the tee going to the sump is the reason yours flows much faster. Yours is about 4" lower. Driscoll's will always drop to the level of the tee (without surface skimming) but his sump is large enough to take the water volume. Even if he decided to use additional utubes to surface skim it will still flow at the same rate because the tee is set as high as it is. The potential airlock would be greater because of this. It's better left as is to bottom siphon.


Right, i should have went with larger pvc, but having both low and high intake is nice.


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