View Full Version : Pump volume required for second filter

04-27-2011, 07:23 AM
Hi guys,

I am planning on adding a second filter to my tank. I have a 65g tank with a Fluval 304. I am going to need more filtration as time goes on and as I fill the tank to capacity. I am planning on building a DIY filter from a piece of 150mm (6") pvc pipe filled with bio-balls or similar and was wondering what flow rate I need to look for in a pump to be suitable? How many times should the tank be turned over per hour and is it different for a second filter?

Thanks for the help.

04-27-2011, 12:48 PM
If this was your only filter, I would say at least 4 times (so 260 GHP). As it is your second filter, I would think you could get away with a little less.

I find this idea very interesting. I would love to see picks on how you build this. thumbs2:

04-27-2011, 01:10 PM
I will definitely post a diy thread once completed.

Thanks for the info too.

04-28-2011, 12:41 AM
I just had a thought while looking at possible pumps. They all lose quite a bit of power with the higher the pump needs to push water. Do I need 4 times tank volume coming back into the tank, therefore needing quite a bit larger pump, or do I need 4 times the tank volume to get sufficient flow with the pump height?

04-28-2011, 01:26 AM
As this is a second filter, you could get away with 3 to 4 times turnover of flow going into the tank

04-28-2011, 07:40 AM
Thanks for that. Is there any formula available to work out the percentage of the maximum flow I will get at any given head height? I will need somewhere between 200 and 260 GPH at standard tank heights (I'm not home to measure). If no formula, is there any pumps you can suggest as being suitable for such a task? I'm hoping to get one that will be able to draw water from the tank without being submerged, hoping to stick it in the stand next to the filter.

04-28-2011, 07:47 AM
most good pumps will have a chart on the side of the box with gph/head height calculations. you want your numbers based after head height is taken into account. for instance, my catalina 2300 only does 600-700gph after 5' of head. also drain size needs to be taken into account as a 1" drain can only do 600-700gph.

as a second filter mainly for bio I would go for 4x+ for a turnover rate