How important are linear inches?

[Steve175]

. . . or is diameter more important . . . or is it how you use what you have

. . .

I'm speaking, of course, of linear inches of external overflow and diameter of drain pipes

Am mid-stage in designing a custom 450G in-wall tank (72" x 48" x 30" w/ bowfront) between livingroom and dedicated, insulated, confiscated, temp-controlled single car garage (heretofore known as the fishroom).

While water quality and flow are my paramount concern, am planning to have the fishroom be a bit of a showcase as well and, as such, cosmetically I would like the tank to be visible from 3 sides. This, however, would allow only a 32" weir for the single external overflow. Drain pipe diameter will not be an issue (can have up to 4 separate 3" bulkheads dedicated to direct overflow to sump).

A dedicated 180G refugium will drain directly into display (increasing directly total overflow) and so I would like a minimum of 3000gph overflow (ideally closer to 4000gph). The sump calculator tells me my ideal linear inches should be ~ 60" for this level of flow. Not sure whether this formula applies to this design utilizing external overflow as well. My design also incorporates a closed loop on a 4-way OM and in-tank Tunze w/ controller but 2 separate remote DSB and large skimmer will, I think, be optimized with higher sump turnover (which 270G sump containing baffles only should support well).

Fishroom will be insulated so noise is less of a concern. Large return pump (probable hammerhead) will be on manifold so exact calc is not critical. Just want opinion on whether a single 32" weir will be ball-park adequate.

If needed, I can add a second 32" weir but only if necessary due to cosmetic (and a bit of space) issues.

Taking some pics and will be starting a tank thread, but this is a loadbearing wall (involving a structural engineer) and I need to sort out this overflow issue (to dictate size of opening in wall) prior to applying for a construction permit. (I do not want to contribute to the mass of tank threads that exist for more than a year before water hits the tank).

Any and all input of this specific question is welcome.

Thanks,

Steve

[silverwolf72]

If your doing it from scratch I would suggest going with an overflow box that runs across the entire top back wall, this would give the best surface skimming and I think it would look better than having the large boxes in the corners

[psteeleb]

here are the typical responses I give:
On you're size system, I would go with minimal 1 1/2" drains and consider 2". with drain you are not only letting water drain but you need to allow for air to escape or it will gurgle.

Prioritize in the following order when designing your pipe systems
1) Drains first - lay this out first as you only have gravity working it. Water must go down and air up.
2) Avoid pockets or long flat runs or you will get air entrapment slowing flow and creating gurgling noises.
3) Use drain fittings if possible, they have a longer radius allowing for a the air to escape and water to flow more smoothly
4) Design your system to drain everything that will drain (sump size and water level issue)
5) Consider unions for future removal. Don't worry about gluing your last piece that is over and goes into the sump.

5) Pump suction is next - short and as straight as possible.
6) Add a union at the pump
7) Valve is optional as long as you can isolate the sump from the pump. A treaded plug in the sump bulkhead works just as well as a valve and saves on money and flow.

8 ) Pump discharge - is last design consideration as you are now pushing water
9) Get the right size pump
10) Union to disconnect
11) Valves to isolate
12) Stay line size or larger on your discharge piping. This makes a huge difference in flow. If you manifold your discharge into more then one return you can drop line size after the split

[downhillbiker]

size matters

[Kannin]

I know that you have an external box... but, what if you added a calflow style box inside the tank, in front of your current box. Would the fact that the new box sticks out into the tank... say, 4 inches, give you more linear flow?

Also... since your fuge is raised above the tank, you could pump water from the tank, directly to the fuge. This would eliminate the need to rob your restricted flow... to feed your fuge. Or plumb a "T" into your CL before the OM... to fed the fuge. Since it is above the display... there should be no risk of flooding.

[Bebo77]

<a href=showthread.php?s=&postid=12726028#post12726028 target=_blank>Originally posted</a> by downhillbiker
size matters

lol i was waiting to see if someone was going to say that...:lol: :lol:

[DrBegalke]

4000 gph thru a sump, even on a 450, seems like a lot. You could go with lower flow thru the sump and use a closed loop for additional current in the display.

As far as the overflow, I think you can get more flow per inch then that calculator. As the water rises, the flow will increase. You will have less of a margin of safety though in the event of a dead fish/etc blocking part of the overflow...