How Much Drain Flow Would This Give Me

[HeavyHittah]

A calfo overflow that measures 36in longx 3in widex 4in deep with 3 1.5" bulkheads??

Also what would be a good pump to use to return it back the DT?

 

[ZOOT098]

hey heavy, i found this calculator, this may help

http://www.aquariumpros.ca/modules.php?name=Overflow_Drain_Calculator

 

[HeavyHittah]

not sure if i understand this

 

[fatman]

You can easily run over 3000 gallons per hour through those bulk heads and still not reach your maximum capacity of the overflow box. I have run a Dart pump off an overflow box 18 long x 3" wide x 6" tall fed by two 2" bulkheads (it was very noisy and turbulent) and a Dart pump moves 3600 gallons per hour. My bulkheads are a total of 6.28 inches square, where your bulkheads are 5.30 inches square or 84% as big. 3600 x 0.84 = 3024 gallons per hour. Your overfow would have a capacity of 432 cu inches, where as mine is 324 cu inches, meaning my box is 25% smaller. My Overflow has 1/4 inch wide notches where as yours would not have notches, if made of glass (as Calfro usually suggests), so your flow through your box could be less limited than mine. Your limiting agent would therefore be your bulkheads and they will probably handle up to at least 1200 gph each. I do not know why you would ever want to move so much water through an overflow though as it would take a huge sump to take that kind of flow through it. I flow a maximum of 1000 gallons per hour through a 40 gallon sump or 800 gph through a 40 gallon sump/refugium. Any faster than this and all the bubbles flow right through the 40 gallon tank and into the display tank, even with bubble baffles. This set up your considering is for a 75 gallon tank. I would suggest an overflow handling around 750 to 800 gph and make up the rest of your tank circulation with a closed loop system or some -ugh- power heads. Even the highest flowing SPS tanks of 75 gallons would only flow around 3000 to 3750 gph in circulation, and most of that would be provided by closed loop circulation with just enough running through the sump/refugium to supply maybe double the capacity of the skimmer(s) so as to also feed raw water to the refugium.

 

[fatman]

hey heavy, i found this calculator, this may help

http://www.aquariumpros.ca/modules.php?name=Overflow_Drain_Calculator

:bounce: It would help some what in designing an overflow but it is impractical as it comes up with holes sizes that are not standard bulkhead sizes. It will not let you pick bulkhead/drain sizes or overf low box size, it only allows the input of the flow you want to move. There is a site on the net that calculates the capacity by number of slots and width of slots and height of water in the slots. I have the program (in Excel) but I did not write down the URL. I can send it as an attachment to real email addresses but not to this site as it will not accept such attachments sent to a PM. :^:

 

[HeavyHittah]

@fatman- keeping in mind that i want the box to be longer if anything(i would also like to keep 3in wide and 4in tall), what dimensions and bulkhead suggestions do you have as to slow down my flow?? I do want a seperate closed loop manifold going around the top of the tank, so the return flow doesnt have to be super, just good enough for a mixed reef. And all other flow can be delivered via closed loop manifold.

And isnt there a chart on the net somewhere that shows bulkhead sizes,how large to cut the hole, and how much gph they can handle?? i thought i seen this somewhere but maybe it was in another of my tank dreams:shock:

 

[fatman]

I am still assuming this is a glass overflow box with no notches and that all three sides of the box will be the same height. Lets calculate first for a box the full length of your back of the tank. Roughly that is 47.5 inches. There would be no sides to the box only a front. If you set your box at just above the height you wanted your water, say 0.5 inch above the bottom of the plastic rim around the top of the tank, and kept water circulating over the rim of the box 0.20 inches deep that would be 9.5 square inches of area, which would equate to 1104 gph. Figuring at 36 inches plus the 3 inch side walls would equal 8.4 sq inches, which would equate to 976 gph. These calculations are based on your providing a pump that would pump the given amount of water at a steady rate. That means if you provide too large a pump the system will want to flow the larger amount that your pump was sending up to your tank. Usually it is safest to design a little large and pump a little small to get what you want. Meaning design for a little larger flow than you need and downsize that flow by using a pump for a flow that you need. That will make up for friction losses to flow not calculated into your plans. Either system could run very well on just two 1.5 inch bulkheads. The bulkhead holes should be drilled so that they are only high enough above the bottom of the interior of the overflow box bottom to have enough space to install the bulkheads. I would recommend an external pump that is flow rated at about 1100 gph (say a Pan World Pump # 50 PX-X). You of course will not get a 1100 gph due to static head loss (meaning the height the water will have to be pumped above the pump to get back into the tank) and friction losses from the piping and fittings (figure on getting 900 to 1000 gph). If you have other questions just ask.

 

[HeavyHittah]

So youre saying i need to make the glass box 36in longx 3in widex 4in tall. With only two 1.5in bulkheads at opposing sides of the box. I would put the box .5in up from the bottom of the trim which this would give me 976gph. In which case i would need the PanWorld pump(rated for 1100gph) to pump in the return??

 

[fatman]

So youre saying i need to make the glass box 36in longx 3in widex 4in tall. With only two 1.5in bulkheads at opposing sides of the box. I would put the box .5in up from the bottom of the trim which this would give me 976gph. In which case i would need the PanWorld pump(rated for 1100gph) to pump in the return??

:bounce: Essentially, yes. The box top edge 0.5 inches up from the bottom of the trim. The bulkheads for the least noise and turbulence should be about 7.5 inches in from each end of the overflow box. With the PanWorld pump you could put in a pretty poor return plumbing system and still handle the flow of 976 gph. The worst that could happen is you put in a really good oversized plumbing return system and then you would move a little more water, but the overflow and the bulkheads would handle it just fine. :^:

 

[HeavyHittah]

how far from the top should i drill the holes?

what size holesaw should i use...a 2 3/8?

will that pump do good on a return manifold? the water will drain from the overflow to the sump(both leading to the skimmer section(probably the octopus 150) pass through the fuge and into the return, where a hole would be drilled for the panworld external and pumped through a manifold. will this work good??

and how come on glass-holes.com the panworld is only rated for 792gph?

 

[fatman]

2 3/8 inches is correct. There should be at least a holes diameter between any glass edge and the edge of a glass hole. Figure your glass edge being the top of the plastic trim piece as accurate enough. The easiest method is to draw the inside dimensions of your box on a piece of upper and allow at least a half inch between the top of the bottom g;lass and the bottom of your drilled hole then see what space is left over above the hole and then that will tell you where your box will be. I can figure the exact height out later tonight if you want me to. The catalog I have in front of me lists the flow rate for the 50PX-X pump at 110 gph. I will email Mike at glass holes and see if he is wrong or if Marine Depot is wrong. Likely it is marine Depot's add that is wrong and then you would need the 100PX-X pump instead. I like a deeper box than Calfo's design and use 6 inch deep boxes as sometimes with a small box there is a space problem and a lot of 1 inch bulkheads have to be used instead of two larger bulkheads. I will calculate the heights later and let you know if that is the case. If it is I would recommend making the box deeper rather than using four 1 inch bulkheads. For a return manifold I would run a 1 1/2 inch return up to the top of the tank then reduce too two 1 inch lines and then put "T's" on the one inch lines for 1/2 inch nozzles.