Difference between 1.5" and 2" drain in overflow

christyf5 · #1 01-20-2010, 04:47 AM

So my 180 gallon was drilled for a 2" bulkhead. I figured since I was working with 1.5" (and I'd have to buy a full 12' of 2" pipe) I'd reduce it and do all the same plumbing. However my durso is pretty much under water above the elbow and makes a lovely sucking noise. I'm trying to make this tank as quiet as possible so for now I've throttled back my Dart pump to about half. In hindsight I probably didn't need the Dart.

Anyhoo, will going back to 2" pipe make much of a difference? I'd really like to run the dart full open or as close to it as possible for extra flow.

fishytime · #2 01-20-2010, 04:50 AM

Have you fiddled with the vent hole?....I wouldnt restrict the drain.....unless you had an emergency drain....

christyf5 · #3 01-20-2010, 04:55 AM

Yeah, if I don't have a cap on it its disgustingly loud. With the cap on, it surges. So I drilled a bunch of holes in the cap so its not so loud and doesn't surge. Its still pretty loud though.

I was thinking of maybe putting a jog in the pipe going from the bottom of the tank to the sump like so: _|
.................................................. .................................................. ....................................| (ignore the dots, stupid thing wouldn't accept spaces to get it there)

but then that just slows down the water in the overflow even more.

I'm currently running a stockman in my 90gal, it's nice and silent but theres a lot of algae growing in my overflow and it constantly clogs the holes of the stockman.

shrimpchips · #4 01-20-2010, 05:10 AM

According to here, the difference in gravity flow between a 1.5" drain (2100gph) and 2" (3300gph) is 1200gph - fairly substantial. Now, I don't know if those numbers are 100% accurate or not, but even if they're off by 25%, I'd say there's still a significant increase in drainage using the full 2".

fishytime · #5 01-20-2010, 05:20 AM

Herbie......

Chin_Lee · #6 01-20-2010, 04:15 PM

Quote:

Originally Posted by fishytime

Herbie......

Once you've had Herbie...... you'll never go back.

mark · #7 01-20-2010, 05:26 AM

I'm running 2-2" Dursos and drilled one vent hole in each cap matched for when first running ~2000gph. Strangely they are different sizes (5/32 and 7/32 just checked with an index) but generally overall they are small. Only about 1000gph now but holes still working, not Herbie silent but the Dursos are really really quiet.

Do remember would get the up/down and sucking in the overflow with cap and no hole, small hole would get the variation in the overflow level but no sucking and still a little noisy but once hit the right hole size, the sound just dropped off level stabilized.

Now if I see the level in the overflow moving a bit, know I have a little salt creep to clear.

Delphinus · #8 01-20-2010, 08:29 AM

It would probably make some difference. Think it's called the "double/quadruple principle", if you double the pipe diameter you get quadruple the potential flow at the same pressures. I'm not sure I'd do the jog. Sorta sucks but it might be worth getting that length of 2" pipe and see how it goes.