Getting a good flow rate

[youngsteven]

I'm trying to increase my flow rate without putting anything else in the tank.
My tank is 200l with an Oase Biomaster thermal 600 filter. That has a flow rate published of 1250l/h which is only about 1/3rd of the ×10 flow recommended and probably only 1/6th in real terms.
I'm thinking of splitting the pipe from my lilypipe and running either another filter or a bypass pump to get the flow rate up. Will this work? Or is this filter already giving me enough flow rate and I'm getting this all wrong? I don't want to add a second set of lily pipes or an internal pump.

 

[hypnogogia]

Splitting the pipe from lili pipe won’t work. However, just to check, are you injecting CO2? If not, the you don’t need to aim for 10x flow.

 

[Maf 2500]

There are a few things can go wrong running two pumps/filters split from one set of pipework. I wouldn't personally want to risk it.

One way to increase flow with your current pipework would be to swap the head unit on your filter for the 850 model.

And as @hypnogogia mentioned above, you might not actually need more flow if you are not injecting CO2.

 

[youngsteven]

Thanks for that, can I ask the reason that it won't work?
Good idea changing the filter head unit, I'll look into that but it still won't get the required flow rate.
Yes CO2 is injected, high tech setup.

 

[Maf 2500]

can I ask the reason that it won't work?

Worst case scenario, one filter pump fails (or you forget to turn it back on) the other pump is going to be pumping the failed filter in reverse. More generally the pumps are going to be somewhat fighting against each other and if one is more powerful than the other they might not play nice. There's probably some other reasons too...

 

[Barbara Turner]

Making sure all your pipe work is as large as possible (most likely 16mm) can make a big difference.
Could you add a extra pump in series running after your filter? There is a slight risk it might suck in air
If the filter seals aren't good enough.

I run a separate stainless steel canister filter and marine dc pump, on max I'm upto 8000l/h
It's a lot of water moving, and not sure entirely necessary. It certainly limits fish choice.

 

[youngsteven]

Could you add a extra pump in series running after your filter? There is a slight risk it might suck in air
If the filter seals aren't good enough.

Thanks Barbara but running in series doesn't increase flow rate, just pressure. I've already got 16/22mm hose, drilled out the pre filter stick and put low density foam on it to increase flow.

Efficiency savings however won't increase flow rate enough I'm looking for help to achieve this without adding extra equipment inside the tank, I'm happy to add lots of equipment outside the tank.

 

[youngsteven]

Worst case scenario, one filter pump fails (or you forget to turn it back on) the other pump is going to be pumping the failed filter in reverse. More generally the pumps are going to be somewhat fighting against each other and if one is more powerful than the other they might not play nice. There's probably some other reasons too...

So if I use two identical pumps so they draw the same flow rate and put a check valve on each of the two to prevent backflow in case of breakdown that should work?

 

[Little]

I’m sure you have considered this, but buying a larger external filter and selling the old one would be a lot easier than getting another smaller one to run in parallel. Apologies if cost is a constraint, I think waiting and getting a standard solution is better than trying something irregular that may not work out and costing more anyway.

 

[Barbara Turner]

Yes, you could run two Oase Biomaster thermal 600 filter with two check valves.
Personally I wouldn't bother with the check valves, there pumps are really reliable. If one pump breaks you might loose all your flow. Check valves are cheap test it with and without. Depends how balanced your pumps are...

Your wrong about running multiple pumps in series..
Yes you will increase the pressure but this will also increase the flow rate.

If you imagine your restriction from all your pipe work like a hole in the bottom of a barrel
Your pump provides the pressure or in this example how full the barrel is of water.
Height of water.

The higher the pressure the higher the fowrate, or the further the water sprays. (higher velocity)
It is diminutive returns, doubling the pressure won't always double the flow rate.


If you add a massive pump like this the pump in the system might have a high flow with the internals removed from your oase pump.

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Stainless Steel Canister Filter Aquarium - Stainless Steel Aquarium External - Aliexpress

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[youngsteven]

I’m sure you have considered this, but buying a larger external filter and selling the old one would be a lot easier than getting another smaller one to run in parallel. Apologies if cost is a constraint, I think waiting and getting a standard solution is better than trying something irregular that may not work out and costing more anyway.

I had thought about replacing the pump but my current pump is the max height that'll fit in the cupboard underneath. Are there any canister filters with 2000l/h and less than 50cm tall?
There isn't really a cost restraint for getting the right setup.

 

[Little]

I use sumps so someone else will be better to advise about canister filters.

I have heard the fluval fx range are far more powerful than Oase and shorter / wider.
My understanding is the tradeoff being no pre filter and no integrated heater (so would also need an in line heater).

I’m sure some filter expert will jump in and suggest something as an alternative to the parallel filters method.

 

[Aqua sobriquet]

You don’t mention whether you’re happy with the filtration or not. I appreciate you’ve said you don’t want to put anything else in the tank but a small power head would be a good solution if you can bear it. It’s something others have done to increase water movement in their tanks.

 

[Maf 2500]

So if I use two identical pumps so they draw the same flow rate and put a check valve on each of the two to prevent backflow in case of breakdown that should work?

In theory that would be OK but there might be other risks I haven't considered. The 16/22 lily pipes and unsplit sections of tubing would somewhat reduce flow levels vs discrete pipework but wouldn't make a massive difference.

Are there any canister filters with 2000l/h and less than 50cm tall?

A Fluval FX4 and an inline heater (or subtle in tank one) might be a better solution in your situation.