pipe sizes for internal bean overflow

[AlanM]

I'm researching setting up a 75 gallon non reef ready tank and drilling the bottom for bulkheads (it's not tempered) and to install an internal acrylic overflow. I'd put 3 drains and two returns in there to do a bean type overflow. So five holes drilled in the bottom of the tank.

 

On ridetheducati's current build thread there was a discussion about just how much flow a 1/2" schedule 40 PVC at full siphon can handle. Turns out it's a lot. I'd only want about 5x turnover because I'm putting in an Avast CS1 which I seem to remember that they say works well at about 350 gph, so that's 375 gph that I'm aiming for. I should have about 44 inches of drop to the water surface in the sump which BeanAnimal's calculator tells me should give me 873 gph minus friction and fitting losses. So it seems like 1/2" would work just fine, but the folks on RC seem to always want much larger pipes for their Bean overflows. I can't find exactly why that is in the 200 page thread. I could go with larger 1" pipe on the open channel and emergency because they're supposed to get film flow down the outsides of the pipes, which is hard to maintain with small pipes.

 

Does that sound like a good plan? 1/2" for main siphon, 1" for emergency and open channel and maybe 3/4" for the returns or just split the difference and do 3/4" everywhere so I don't have to buy 3 drill bits. Or maybe it would be simpler to do all 1" bulkheads and use reducers to get 1/2" pipe for the main siphon and 3/4" for the returns so I'd only have to buy one bit and one bulkhead size?

[Integral9]

i havnt read the forum you are talking about, but there is a difference in how much water can be pumped through a pipe and how much water will fall (gravity fed) through a pipe at full siphon. Basically, pump > gravity.

 

Somewhere on the interwebs is a chart indicating max flow rates and max drain rates.

 

Here it is: http://flexpvc.com/WaterFlowBasedOnPipeSize.shtml

[AlanM]

I've seen that chart, but those rates are not vertical full siphon. That chart shows the minimum flow you can expect in that pipe size. Quote from the page:

 

The first set of columns would be the minium you would expect for the pipe size shown using nothing but gravity in a low head pressure situation to power the flow.

 

Also, they assume 6 ft/s full velocity. Acceleration of gravity says that things increase in speed 32 ft/s per second they spend falling. So in 3.5 feet of drop the water is moving way faster than 6 feet/sec. Full siphon can be calculated pretty easily and then subtractions are made for friction with the equations and convenient calculator on this page:

 

http://www.beananimal.com/articles/hydraulics-for-the-aquarist.aspx

 

So that's the theory on the page and where I got the 873gph for 44 inches of drop on a 1/2" PVC. I guess I know it can handle the flow I need, what I'm curious about is anyone's experience running a half inch drain to see if it's just too small to be practical on a day to day basis. Like it's the perfect size to trap a snail and overflow, or it's too skinny once you get a film of protein and gunk on the walls and the flow rate drops dramatically, or it's too flimsy to use and you'll crack a bulkhead by accident, or stuff like that.

[Coral Hind]

This calculator should help you. http://www.beananimal.com/articles/hydraulics-for-the-aquarist.aspx

 

Doing it in 1" gives you the option to use a bigger size later on if needed.

[AlanM]

This calculator should help you. http://www.beananima...e-aquarist.aspx

 

Doing it in 1" gives you the option to use a bigger size later on if needed.

 

haha, yep, we were posting at the same time. That's where I got my number from. I'm interested in practical considerations to running a half inch drain. I know it will flow at the right rate.

[steveoutlaw]

Alan - I have a Bean Animal setup on my 240g using 1" pipe. I have an Eheim 1262 as the return and I have the ball balve about 75% closed. I wouldn't go any less than 1".........the smaller the pipe the easier to clog.

[AlanM]

Alan - I have a Bean Animal setup on my 240g using 1" pipe. I have an Eheim 1262 as the return and I have the ball balve about 75% closed. I wouldn't go any less than 1".........the smaller the pipe the easier to clog.

 

Thanks. I will have a reeflo blowhole 1450 as the return. Maybe in the basement if I work out issues with bean overflows and horizontal runs (which BeanAnimal disclaims as ruining the concept) I would run it full out and it should do fine with 15 horizontal feet and 10 vertical feet, but under the tank I will select a lower speed.

 

If you're running the eheim and getting like 1k of flow through your 1 inch at 75 percent closed, though, I'll have to run mine at around 90 percent closed or put an orifice on the end that's easy to clean when it clogs or something if I use 1" pipe.

[BowieReefer84]

Put a union right before the gate valve for removal and cleaning.

[Integral9]

Is there a formula telling you how high above your intake the water level will rise?

[BowieReefer84]

Is there a formula telling you how high above your intake the water level will rise?

 

You can dial it in how high over. Mine runs a about 4" inches above the intake. Just close the valve and open it just slightly, and that is where the waterlevel will be.

[Der ABT]

how far down are your holes drilled (full syphon and others)? going to need to figure this out as well.

 

im going to go 1 inch as well

[BowieReefer84]

how far down are your holes drilled (full syphon and others)? going to need to figure this out as well.

 

im going to go 1 inch as well

 

I used 1" straight pipe up from bottom of tank in the internal overflow chamber. I didn't mess with all those "T's" and what not. I put a 45* on the secondary and emergency to smooth the flow, but that is it. Main siphon is just a straight pipe... So three pipes all 1" each higher than the next. Works like a charm.

 

Here is a video I had shot:

http://flic.kr/p/deqUnY

 

Ignore the thing hanging on front of tank.