Sizing a bean animal drain.

[Randys]

I'm in the process of designing a new set up and plan on using the bean animal overflow style.
From the research I've done it looks like a 1-1/2" diameter drain will get me in the ballpark of the flow rate I'm targeting.
Is there any disadvantage to stepping up to a 2" drain? What happens when you use a drain size that's too large?

 

[ragin_cajun]

That's what I did. 1.5 inch would have done me just fine, and I bumped it up to 2 inch drains. So what size pumps are you gonna run, what's your flow rate gonna be?

 

[Randys]

Well..........you know how it goes..................
I was originally thinking about an 8 foot 240 BUT if I build the stand 30" wide instead of 24" I'll be able to slide my 4 foot long sump inside. So NOW I've convinced myself I need a 300 gallon tank! LOL

I'm targeting around 10x on the 300 gallon tank. So 2,500-3,000 gallons an hour with an external Iwaki pump. I may even use two Iwaki pumps. I've already got one on my 90 gallon Mbuna tank so I figured if I used two on the 300 I would have back up pumps for both tanks.

What flow rate are you getting?

 

[Randys]

Well, I purchased a Reeflo Barracuda pump that will get me 3,300 gph with about 8' of head (once you figure in height, horizontal runs, and elbows). The Reeflo uses much less power then comparable pumps.
I'm still torn between using 1-1/2" or 2" bulkheads. I would rather step up to the 2" size but, since I plan on using schedule 80 bulkheads, that may require making my overflow wider.
Does anyone have experience running 1-1/2" drains with this rate of flow?

 

[714car11]

Im using the jebao 15000. Im using 1.5 pipe for my main drain. Pump in rated at 4000 gph. I think im getting 3000 gph once it goes in the tank.

 

[pdxmonkeyboy]

a 1.5" pipe at full siphon will EASILY move that much water. if you want I can just do the math for you. For that I need to know what type of 1.5" pipe and the amount of head (vertical distance between the start and end of your overflow pipe).

it's all about the head height as that falling water is always accelerating and pulling more water in. typical flows for 1.5 with 3 or 4 feet of head is around 3 or 4 thousand.

in short.. plenty.

 

[Randys]

Thanks for the offer!

It looks like the vertical drop from the display level to my sump will be around 3 feet.
I planned on using standard schedule 40 because it's so readily available. Would it be worth the effort to use SDR pipe and fittings? I thought it may be more of a hassle to find those fittings and if you used schedule 40 fittings you would be giving up any advantage you gained with the larger ID pipe.

 

[pdxmonkeyboy]

well I didn't do the exhaustive math since I'm stuck in traffic. but based on your fall length (3 feet) the water velocity is going to be around 13 ft/s. That is well below the max water velocity (flow) for 1.5 schedule 40. looking at a handy chart.. you are around 4800 gph. so, the answer to your question is no, you don't have to go to 2".

 

[DN328]

You may end up having to close a 2" more to reach laminar vs. a 1.5, no? For a 300G I think you'd be more than fine, imo.

 

[jandb]

I'm running the a 2" bean animal with a reeflo gold super dart and it's fine. I don't have to choke it back too much but if I ever decide to put a hammerhead or something bigger in it there's plenty of adjustment left.