Turn over rate??

[john73738]

For a 240 gallon 8' tank is roughly 6x filtered turnover OK?

Going to have 1 pump at each end of the tank rated at 681 gph figured in head loss to achieve the 6x turnover.

Add 2 230 gph powerheads with DIY spraybars (no filter on these)

Thoughts please.

Thanks

 

[VLDesign]

IMO turnover only counts on filtered water. 4x is what I use on both my 300 and 1500 gallon tanks and have no complaints.

 

[john73738]

Cool thanks.

 

[Toby_H]

There is an age old "Rule of Thumb" that suggests 10 times turnover and this is a wonderful "Rule of Thumb"...

But when we start talking about very large tanks or when we start talking about refined filtration, we throw all "Rules of Thumb" out the window and replace them with logical design.

You absolutely need enough water movement to reventdead spots and to circulate the newly oxygenated water from the surface of the tank to the other regions of the tank...

Most people want enough current to move waste into filter tintakes. If you choose not to supply flow to acheive this it becomes yoru responsibility to thoroughly vacuum the tank with weekly (at least) cleanings...

When people start debating what counts as "turnover" they are entering a useless debate, as by the time you are providing supliment water movers (i.e. powerheads) you are moving away from "Rule of Thumb" filtration and entering the wonderful world of custom designed filtration...

 

[dawnmarie]

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[john73738]

There is an age old "Rule of Thumb" that suggests 10 times turnover and this is a wonderful "Rule of Thumb"...

But when we start talking about very large tanks or when we start talking about refined filtration, we throw all "Rules of Thumb" out the window and replace them with logical design.

You absolutely need enough water movement to reventdead spots and to circulate the newly oxygenated water from the surface of the tank to the other regions of the tank...

Most people want enough current to move waste into filter tintakes. If you choose not to supply flow to acheive this it becomes yoru responsibility to thoroughly vacuum the tank with weekly (at least) cleanings...

When people start debating what counts as "turnover" they are entering a useless debate, as by the time you are providing supliment water movers (i.e. powerheads) you are moving away from "Rule of Thumb" filtration and entering the wonderful world of custom designed filtration...

Eloquently put, and great advice. I have decided on...

5x filtered turnover
3 powerheads running 2 @ 290(ish) gph 1 @ 100-150 gph
1 for a spray bar for surface agitation
1 for underwater circulation (stir in filtered water)
1 under the viewing window for churning up poo and sending it to the filter intakes since I am going with sand.

Thanks for the help.

 

[dawnmarie]

Sounds like plenty.
I would be curious to see how you are going to layout your suctions/drains and returns.
Any pictures ?

I am unclear on this.

Going to have 1 pump at each end of the tank rated at 681 gph

Will you be using a sump or a closed loop system ?

With either setup you could use the returns from the main pumps to power two spray bars.
Done carefully this should give you adequate surface agitation and circulation thus allowing you to add the powerheads only as needed to correct return flow deficiencies.