Mak 4 and 1 1/2" stand pipe question

newgeek · #1 05-29-2003, 02:26 AM

I know there are threads about this topic and I think I am just looking for reassurance here. I am concerned about my overflow not being able to keep up with my pump here are the details, Mak 4, 5 feet head and the overflow has a 1 1/2" Durso stand pipe. I did a test firing with the new sump I built (leak/pressure test) with a new Mak 4 as the return and I am blown away at how much this unit puts out so I am a little concerned the stand pipe will not be able to keep up. Anyone have experience with a similar set up? Thanks everyone.
Have a great night,
Kelly

DJ88 · #2 05-29-2003, 02:52 AM

Kelly,

I ran that set up myself. It will handle it just fine. I have ran ~2000GPH or more through it there abouts.

kari · #3 05-29-2003, 03:23 AM

Kelly;

I haven't tried that pump before and nothing beats trial an error experience. If you are in a scary situation, I can calculate the required ID of return pipe for you. However, I would need you to provide some plumbing info (eg. materials, fittings, lengths and sketch of plumbing with dims) and a copy of the flow diagram for the pump in question. The easiest method is refer to someone else's setup with the same pump and similar plumbing and apply a safety factor that you feel comfortable with. Or just apply a huge safety factor and be done with it. An over flow that is too large can not be a problem IMO yet the opposite can be painful.
Anyway, going beyond the Blah-Blah, it is better to overkill the overflow for future considerations such as added circulation. Don't undersize!

The guy with the rusty Bernouli Equation.

kari · #4 05-29-2003, 03:34 AM

Let me shorten the long winded last post.

Question: Mak4 at 5ft head - - flow equals

Lets skip the fluid mechanics crap

Kari

StirCrazy · #5 05-29-2003, 04:22 AM

I use a 1.5" overflow and I can barly flow 1100 gph through it. now I have two 90 degree bends in it so that will be a bit of a factor. but I would guess you would be ok if you are fairly strait. I think the "book" max flow for free falling water through a 1.5" pvc pipe is about 1700 to 1800 gph but i would have to find my book to be sure.

Steve

Delphinus · #6 05-29-2003, 02:24 PM

Is your overflow 1.5" all the way to the sump?

I use a 1.5" durso/stockman overflow but under the tank the line is only 1" and it has two 90 degree bends. Let me assure you, that setup can NOT keep up with a mak4. I can overflow the tank with my mak4 on full (72g tank, 20g sump). The standpipe itself is not the bottleneck though, it's the plumbing underneath that's the issue. Just thought I'd mention that, because it's a significant factor. If I recall correctly I thought Dursos were supposed to be one size up from the plumbing so a 1.5" Durso is a good size for 1" pipe. Or something like that, I don't remember exactly anymore.

StirCrazy · #7 05-29-2003, 03:32 PM

ya mine is allthe way to the sump.. the numbers I posted were for a strait peice of 1/5" pipe no restrictions or anything.

you can solve the problem by putting a valve on the discharge of the pump that is "T"ed off the main return line. by opening this valve you will be able to divert some of the flow back to your sump and reduce the amount going to the tank.

Steve

DJ88 · #8 05-29-2003, 04:38 PM

I have to chime in.

WIth a 1.5" durso with my reduction down to 1.25" I had my AMPMASTER almost fully open and it handled it. It didn't even strain with a MAK4. When I was pushin it with the AM3K it was literally shaking from the velocity of the water passing through it. And I mean shaking. But with my MAK4 it was whisper quiet and never flinched. Fully open, full throttle, balls to the wall. I didn't need to restrict the flow of the MAK at all.

Do a search for my plumbing test and you will see the flow I was getting.

Something is not computing there. Sorry to say.

newgeek · #9 05-29-2003, 04:50 PM

Thanks for all the replies everyone, The Durso will be changes to 1.5 all the way straight down to the sump. I did manage to find the flow calculator on reef central also and it recomended 1.43. I am cutting it close but I think with 5 feet of head and going through a SCWD (I have read they restrict flow somewhat) it should work just fine. Now I just need some sand for my DSB. Thanks again everyone for your time and insight.
Rock 'n' Flow
Kelly

Delphinus · #10 05-29-2003, 05:49 PM

It "computes" just fine, Darren ... there are merely other variables at play that just aren't identified. 1.5" stockman standpipe, 1" pipe to the sump, two 90 degree bends. Cannot keep up with a Mak4 at about 3' or 4' head.

It could be the teeth itself of the overflow, the length of the standpipe (height), or it could be that the first 90 degree bend is in the bulkhead itself. Wasn't interested enough to figure out the exact reason, but hey if you're interested enough and want to find out, you're more than welcome to come out anytime, Darren.

But, it's not like there's an issue here for me, this works out just fine. I don't WANT a full MAK4 kind of turnover from my sump -- I don't want a microbubble phenomenon. I currently run the MAK4 at about 40% as the sump return, the rest drives the skimmer. It's actually working out, at least for the moment, seemingly just fine...