Flow thru a sump - help please? has my aquarium builder conned me? Evening,

[Giles Guest]

My aquarium builder has just gone bust and I'm worried conned me with poor equipment so would really like some advise / help about flow rate through a sump.

I've just replaced my 4' marine tank with a new 8'x2'x2' tank. The guy built a sump with three sections; (1) protein skimmer (2) refugium to be used with either miracle mud or sand and caulerpa or chetomorph (any advice welcome) (3) chemical filtration = carbon refractor to roaphos reactor to UV to ecoaquilizer.

The return pump is only doing 400 litres per hour (tank volume = 800 litres = 0.5 x circulation per hour). His argument was that the main tank can have high circ but the algae needs a slow flow rate. Is that true? The return pump rate seems REALLY slow.

Also, my chemical filters roa, carbon, UV etc need 2000 litres per hour and are on a different accurate pump but that means sump water is being chemically filtered 4x (2000 lph) before it is being sent back to the main tank (500 lph) which I think might over sterilise the water.

Really unsure what a good SUMP flow rate is and whether to upgrade the return pump or to downgrade the chemical filter pump? Please help - I'd really appreciate it.

 

[mr_X]

skip the miracle mud. it's bogus IMO. you don't need it. just put some sand in the bottom of the fuge.

it's not true that algae needs slow flow rate. i would use a pump that pushes at least 3500 liters. somewhere between that and 5000 would be my target pump.

 

[David S]

Agree with Mr x regarding MM,I would definately go with a deep sand bed and chaetomorpha or just live rock.As for water flow I would personally go with at least 5000l/h.The slow rate would have just been for the refugium part of the sump with MM in it otherwise you may pump the miracle mud every where if you don't have a slow compartment for the fuge.

 

[Mark Hewitt]

400 litres per hour! I'm getting around that on my external filter! My tank is 135 litres and I'm quite disappointed by the flow, if I had 800 litres I'd be mortified!

 

[cmor1701d]

My tank (125g - 473L) has a return pump from the sump of 2725 Litres per hour. That's over 5 times turnover per hour. You want a reef tank to have 10x - 30x flow. The rest of the flow can be via power heads and/or a closed loop system.

So yes, your tank should have about 4000 - 5000 litres/hour of flow just from the return pump.

 

[Floyd R Turbo]

Did you measure the flow rate, or are you going by the flow rate listed on the literature from the manufacturer? Keep in mind that the flow rate will be reduces by the head pressure, and if your guy didn't install the right size tubing, the flow could be further reduced by restriction. The best way to measure the actual flow rate is to find a container and time how long it takes to fill it, do that about a dozen times, eliminate the 'high' and 'low' times, then figure out what the actual flow rate is.

I was surprised to find a Mag12 with 5 feet of head producing only 433 GPH when it should have been 800-1000. This is when I discovered that the 3/4" output nozzle needs to have a 1.5" hose connected to it, or else the flow friction increases exponentially. Compound that with the fact that the bulkhead is only for a 3/4" connection and I started to wonder how many other people have this problem, but are completely unaware of it.

 

[cmor1701d]

Floyd is correct with respect to the Danner Mag pumps. Other external pumps don't have the same requirement, though according to the Danner literature that should apply to all pumps.

In my discussion with a Danner representative she did say that for aquarium use with 5' or less of pvc the difference would be very slight. The longer the distance the greater the fall off due to friction within the pipe.

 

[Floyd R Turbo]

That's doesn't jive with the current setup I'm having the problem on. It's a direct shot straight up through 3/4" ID flex hose, then 3/4" bulkhead, more 3/4" hose, and a 90 over to a dual loc line nozzle. With a clean pump, it's running at 433 (measured). I still have to find time to swap out the lower section of hose with larger ID hose and see if it makes a difference.