what size return pump?

Ideally you want a sump design where you can redirect some of the flow around your DSB. That way you can fine tune your DSB flow rate, and have a higher turnover return pump. Personally I'd go for more like 10-15x, i.e. 5000-7500 l/hr effective, which given a head of about 1.4m means you need a pump nominally rated at more than this.

As an example, here's the flow graph for a pump nominally rated at 450 l/hr, but with a 1.4m head it only achieves about 300 l/hr.
Info: Pump Head vs Flow Rate - Overclock.net - Overclocking.net

In summary, I think you'd be well served by a Lifetech AP5800 or similar pump. It's rated at 12,000 l/hr, but probably achieves around 8000 l/hr with a 1.4m head and some piping, which is around 16x your system volume. Provided of course that you divert some of that flow around your DSB, as it's probably too much flow for that.

You could also install one of those clever-dick flow mechanisms at the outlet (I forget the name) to create varying, turbulent flow in the display tank.

Q

 

I would say it all depends what you want or want to achieve with it. My new tank's head will be only 1.2 high and I split the return pipe in to 2. One side is a normal return pipe on the far end of the tank and the other one is attached to a live rock stand drilled full of holes. I'm using a 3000lph Rio Hyper flow pump. Tested it the other day and it works the bomb .
You want good flow inside your tank, not a too fast turn over. Your skimmer will remove more stuff from the water and the flow over your DSB won't be too strong. Just my opinion anyway

 

I would say a 2500 l/hour might be SLIGHT overkill for a 500 litre tank. 1800 to 2000 litre / hour will be more than good enough....
You do not want too fast flow through your sump.....
Otherwise the sump's filtration does not get a chance to work as it should.....

And oh yes - you want to aim for a 2 to 3 times SUMP water volume turn-over, in sump water flow....

 

Hi guys.

I have the same question here.

I too have a 500l tank.

Was think of getting a dc pump.

What would be suitable?

Jacod dct 2000 or jacod dct 4000?

 

Great thread , sitting with same issue. Thinking of upgrading return pump. Like the D.C. Cause you can adjust flow nicely. Was looking at small red devil, wonder how that compares to the Jacod.

 

My return runs across my sump then up, would this increase the head height ?

 

About 15cm, just a touch too shallow. I definitely think my return is too low, , but the tank is running nicely, so am thinking to wait a bit, unless I find a bargain second hand.

 

Hi Guys, stupid question, why cant you divert all the flow to the return pump chamber, bypassing the DSB, and then branch off the return line to the DSB with a ball valve to control the flow.

 

Neat solution, I like it. Surely if your return pump was big enough, you could still branch off and achieve the same results but with one less pump.

 

Forbes, sure that would work providing your flow back to your tank does not drop too low.

 

So higher flow over dsb is better ? To what degree can you increase the flow ?

How does flow rate affect sediment ?

Adding more aragonite to my dsb today, try to get al least 18cm

should light cycle in dsb mimic tank, or more beneficial to run 24hours or inverse to tank. ( of inverse how dark does it need to be during the day ? ) I have some macro algae in my dsb compartment.