Tank Turnover Rates

[scriptmonkey]

In my introduction post I went over some of my equipment purchased alread and hinted at some of the issue ( I perceived) I was going to have with flow rates to my sump due to having the Overflow of my 75Gal Marineland CornerFlo tank only going through a 1 inch bulkhead. I was reading that optimal flow rates were 10x-20x tank volume so seeing Marineland quotes 700GPH, I knew I was going to come up lacking. After going through most of the stages of grief I thought it was time to engineer up and come up with a secondary plan which was to use the second drilled hole that was meant for the return and create an additional overflow. Off to the Lowes!! Then this happened:

Welcome! The turn over rate is more of a flow rate. You can achieve large flow rates by using power heads/wave makers inside the tank.

HUGE thanks Jaime!

So...armed with the proper term "turn over rate" I hit the searchy button and it seems like 4x turnover per hour through the sump seems to be a good number. So before I head off and return my gaggle of PVC parts in 1 1/2" and 1 1/4" to Lowes am I missing something? As nice as it would be to have a redundant drain (one is none, two is one ), will Ms. Scriptmonkey get her dream of having no pipes seen now that I do not have to come up over the back for the return?

 

[fabutahoun]

Welcome to R2R

Turn overrate is the amount the will overflow from tank to sump so 700gph is more than sufficient.
To achieve the optimal flow rates you need to add wave-makers like vortech or jebao inside the tank

I would recommend to have 2 drains at least one as main and other as an emergency, the emergency one should be a little higher than the main drain. that is when the main drain get clogged the emergency will kick in. it just happend to my friend few days ago he had only one drain, he ended up with overflown tank and sea water all over the carpet and empty sump with burnt return and skimmer pumps

Fadi~

 

[mcarroll]

So...armed with the proper term "turn over rate" I hit the searchy button and it seems like 4x turnover per hour through the sump seems to be a good number. So before I head off and return my gaggle of PVC parts in 1 1/2" and 1 1/4" to Lowes am I missing something? As nice as it would be to have a redundant drain (one is none, two is one ), will Ms. Scriptmonkey get her dream of having no pipes seen now that I do not have to come up over the back for the return?

That's usually the flow rate I target.

Anywhere between 2x and 4x works out in most cases. Important to realize in case the pump you want doesn't hit right at 4x.

Don't sweat if you're somewhere else in that range with your final pump selection and plumbing layout....or even up to 5x. It just doesn't make sense to spec. a pump larger than 5x as you typically end up spending too much money (up front and in power use) and generating downstream bubble and noise problems....while not buying your tank much of anything in the way of benefits. That money is always better spent on better powerheads or more powerheads for the display.

2¢

 

[HolisticBear]

I was reading that optimal flow rates were 10x-20x tank volume so ...

Anywhere between 2x and 4x works out in most cases. Important to realize in case the pump you want doesn't hit right at 4x.

I recently got back into the hobby after a long break (10+) years. Back when I was in the hobby, 10-20x was the normally quoted number. However, the current recommendation is ~4x. Not sure what year it changed over, but just an FYI on those 10-20x number. I imagine people now prefer more 'contact' time in the sump (skimmer, reactor, fuge) and we have access to greatly improved powerheads (propeller & dc).

 

[mcarroll]

I recently got back into the hobby after a long break (10+) years. Back when I was in the hobby, 10-20x was the normally quoted number. However, the current recommendation is ~4x. Not sure what year it changed over, but just an FYI on those 10-20x number. I imagine people now prefer more 'contact' time in the sump (skimmer, reactor, fuge) and we have access to greatly improved powerheads (propeller & dc).

I'm not sure on the timing either, but it might have been the year the Tunze Stream 1 came out. (2002, per their website) Or however long the transition took the Stream to go from from introduction to mass popularity.

As I recall everyone who was serious was using closed loops up to that point.

Turnover numbers were a lot harder to achieve back then, and I suspect that flow velocities were high enough to make up for "low" in-tank flow rates. (Not without some complications and expense, of course.)

Now you see people spec'ing 40x and even upward toward 100x for powerheads.....I think because velocity is so low in some powerheads. (This avenue can still be expensive. )

 

[scriptmonkey]

40-100x? That seems really extreme. Like seeing all your corals and fish in a swirling vortex of doom type of extreme.

Thanks to everyone for helping me be smarter.

 

[rtparty]

Sump turnover and flow in the tank are two different things. I don't even consider my return pump flow as part of my in tank flow. My current setup has about a 7x sump turnover rate. Little high so I may bring it down. My in tank flow will be 30-50x my tank. So on a 50g tank I am shooting for close to 2500gph with my powerheads