? about the diy overflow

[keiths]

I found this design on another forum. He used to have the same design as normal but he shortened the first tube. What do you guys think?

Also does anyone know what the flow rates for these are?

 

[ichthius]

This design is fundamentally flawed. The out flow tee has to be higher than U (two elbows) that is in the tank. The way this is set up it will break the siphon if the water flow stops.

If you go back to the drawing I posted you will notice that the siphon brake (the out flow tee or the hole melted in the glass is higher than the end of the glass tube or in the case of the pvc the double elbows in the tank.

The basic principle is that you have a complete circle or spiral of tubing that is uninterrupted from it's intake to its out flow. On the pipe models just consider the vertical part in the tank as a sand pipe and the intake is not it's top but rather the bottom of the stand pipe.

 

[keiths]

Where is the instructions for the good one then? I can't seem to find it anymore.

Also is it ok to use pvc that is 2"?

 

[ichthius]

Towards the end of my use of this type of device I got completely away from one inch. It's much less expensive than 1.5 or 2 inch but they just move so much more water.

If you take the picture of pipe above if you put 6 inch pipe between the last elbow and tee to elevate the out flow it will work. I like to make my out flow tee at least 4 inches higher than the end of the vertical pipe imidiately in the tank.

I don't know who to give credit to for making this nice drawing but here are the basics, the only thing I do differently is to make the EE elbows out of the tank lower than the ones in the tank and make the F tee higher than the EE tees in the tank:

 

[keiths]

That diagram brings me to my next question. For the intake all the diagram is using is that pipe labeled B. However a lot of people use a 90 on top of that pipe. What is the difference, does one work better than the other?

 

[ichthius]

You have to put a screen on the pipe or your fish will go down the drain. If you're surface skimming the easiest way to put a screen on is with an elbow and a slotted pipe or bulkhead screen.

I usually would just wrap the end of pipe B with gutter guard from home depot and secure it with a couple zip ties. If you do it right you can then slide it off for a quick rinse and have it slide right back on.

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[redchaser]

I'm about to set up a 75 gal native tank, and was leaning toward a canister, however after seeing a lot of the DIY sump and overflow plans here and elsewhere I think I'm going that route for 2 reasons. 1 - I'm cheap, and 2 I really like the plastic drawer setup, it seems like that will make changing and cleaning the mechanical fliter media very easy vs shutting down, opening and cleaning a canister.

My question about the PVC DIY overflow

oops, I hit something wrong and submitted too soon. My question is how do you prime this overflow to start running in the first place?

Thanks.

 

[CHOMPERS]

Both of the bottom loops have to have water in them. The one in the tank takes care of itself. You have to pour water into the one outside the tank through the vent tube. Then you suck the air out of the top loop using the air check valve. Put a piece of air line on the check valve so you have some warning prior to inhaling a lung full of tank water.

 

[redchaser]

Ok,

One last question for those that have used this kind of overflow. On another forum (fishlore) they had a thread about this same overflow and listed the following chart for flow rates vs pipe size. Does this look about right to you guys?

3/4" = 330 gph
1" = 600 gph
1 1/4" = 910 gph
1 1/2" = 1,300 gph
1 3/4" = 1,800 gph
2" = 2,350 gph
2 1/4" = 2,960 gph
2 1/2" = 3,650 gph
2 3/4 = 4,450 gph
3" = 5,280 gph

 

[CHOMPERS]

I just told someone that as soon as a thread makes it into the Sticky Section, that no one looks at it anymore.



...but yes, that looks right.