Flow Rate Help

[danni_69]

Hey guys.

I'm going to be getting a custom made reef tank, and have NO idea how to calculate the size of pipes i need to get the flow rate what i want going thru my sump and tank. Can anyone help me please???

The tank dimensions are going to be 39" long, 18" wide, and 20" high of water (22" to the top of glass). it will have the corners cut off at 3.54 inch making a 5inch cut of glass on the corner.
Sump dimensions are, 35" long, 14" wide, and 16" high (only filled to 9.5" high with water)
This makes the water volume (before live rock and sand is added) 262 UK litres for the tank, and 76 UK litres for the sump. Total water volume will be 302 UK litres.
So I would like to go for 15 times filtration (thru the sump), but as said before, I have no idea what size pipes I need, to get this rate right. I would also like to put a 4500 lph pump going from the sump to the tank (filtered water) .

Any ideas of any one who knows the answer, I would much appreciate your help

Thanks very much.

 

[TigerIssey]

What do you mean by cut of glass at the corner??

 

[danni_69]

its going to be six sided rather than four sided

so instead of a 90 degree corner, its going to be a diagonal corner

l l
l l
\______/

 

[scott133]

your probably best pm bigc or skiflech

they would be able to help you out with that question

 

[TigerIssey]

Right, do you have holes or a hole drilled in the base or bottom of the tank as it is custom made?

Are you having weirs??

If you have a hole you will need a bulkhead fitting to fit the hole. The pipework from the tank to sump needs to be as large as you can get it with the bulkhead you have.

I will pm you a link, jury is out at the mo which forums can be linked and which cannot.

Have a look at this link Melevsreef have a read and see if you can sort the piping from it.

Read the articles at the bottom aswell, Everything you want to know about sumps 1,2 and 3.

 

[danni_69]

cool thanks. one other thing too.. is the flow thru the sump affected by how wide the gap is in between the 2 or 3 pieces of glass making the different sections and weirs (i think thats what they are called)

 

[TigerIssey]

It may well be, I have just measured mine and they are 1" apart, I think that is pretty standard.

Don't forget though as I said in PM, the flow of your 4500 lph pump will be reduced by the negative head. What this means is that it is pushing water upwards against gravity, therefore the flow rate will be reduced from this.

 

[Crazy fishes]

What you must remember is the return pump is the thing which dictates flow through the sump provided the pipe work is large enough. Therefore if you use two drainage holes from the weir (one slightly high than the other) and 35 mm drainage pipe ( I think is the 1.5 inch stuff) it shouldn't limit flow. Next you select a pump that returns 15x your sump volume at a pressure head of x. X will be the distant from the water surface to the return hole in the tank. Simple.....

Regards

 

[jtnova13]

302L=~80 US gallons?

I believe you will have 1" bulkheads which are the limiting factor in your display tank drain and return no matter what size piping you use.

How high will you have to pump water? This will determine how much head you have to overcome.

if you are looking to get 4500 lph ~ 1170 gph, and you are pumping up 4 feet or so, you will need to oversize your pump. It's probably best to do this anyway and just put a valve on both your drain and return piping so you can regulate the flow.

Sorry to work in US, I really should use metric since I'm an engineer

 

[owlbassboy]

would 15x through the sump not be a bit fast?? i always thought about 5x was better but maybe that was just for a dsb sump.

 

[TigerIssey]

I have to be honest, I only have about 5x turnover through the sump. If you are using a 4500 lph pump you will probably be fine to just use that. You may find it is too powerful.

I have just been and priced up my new 6ft tank. I was advised for a double return for this tank to use a 3500 lph pump which will give me the turnover through the sump that I need.

I think 4500 may be too much, why exactly do you want 15x. Have you been advised by anyone else of this??

 

[jtnova13]

I have to be honest, I only have about 5x turnover through the sump. If you are using a 4500 lph pump you will probably be fine to just use that. You may find it is too powerful.

I have just been and priced up my new 6ft tank. I was advised for a double return for this tank to use a 3500 lph pump which will give me the turnover through the sump that I need.

I think 4500 may be too much, why exactly do you want 15x. Have you been advised by anyone else of this??

I agree, I'm using a 600 gph pump on my 90 gallon which is just over 6x

 

[SkiFletch]

Agreed, you want somewhere around 5 times flow through the sump. More is fine, it's just noisy and electrically inefficient (not to mention unnecessary)

So with an 80 gal system, you'd want ~400gph of flow. Dual drains as crazy fishes implied is a MUCH safer way to do it. 1.5" is a little much for that flow though, you could get away with 1" bulkhead fittings/piping. 1.5" would be safer, but 1" is OK. Once you do that, select a pump which can supply the appropriate flow after head pressure loss. Assuming the sump tank is in the "typical" position around 4-5 feet below the top of the display tank, you'd want to select a pump with 400gph at 5ft of head pressure. Since I'm pretty sure the location listed in your profile is not in the US, I'd suggest an Oceanrunner pump, probably the 2500lph model. They have decent head capability and will probably deliver the required flow at that pressure drop. Return piping should be same size as the drain, or one size smaller if you wish to save on cost for plumbing parts so as to not restrict the pump.

Are you planning on drilling the sides, or the bottom of the tank? Have you considered weirs to keep critters out of the area?