Flow vs Turnover

[NeO]

David, this does not make any sense

Cooling effect is another, my basement is a cooler
I'll end up having 180g show, 129g sump, 125g frag. 75g fuge

If your basement is cooler in the summer, why you don't keep the water longer in there?


And I think that over 90% the gas exchange/aeration is done by the skimmer.

Now if you tell me that you are going to split the 2100ghp through all of your tanks, 180g, 129g, 125g and 75g, then it is a different story.

 

[Matt L.]

...So often I see posts on RC: I have 900X turnover rate in my SPS system .....LOL It's always some guy that just put a pair of tunze or the like in use so he does the math @ 40,000 GPH in a 75 ....
or you see "well my return pump is a xxx and 3 magdrives on closed loops and ..etc so my turn over is ..."

That guy is full of it. The fact that its on RC is of course no surprise.

To add up the flow from your powerheads and Tunze's within a tank and use that to compute your turnover rate is dead wrong. You can't do that. Turnover rate only works for volume entering/exiting a tank.

Matt

 

[NeO]

Based on the amount of detrius that I am able to vacuum out of my sump
and my skimmer output

BTW, if you have high FLOW in your tank, the detritus are going to be suspended in the water column, and eventually will go down to the sump anyway.
To give you an idea, I'm running a T4 for the return, base on RC head loss calc. the T4 is given me 829gph and I have 2 Tunzes 6100 for extra flow in my 120g.
I do have to vacuum the detritus out of my sump every time I do water change and at least once every 2 mounts I have to vacuum my fuge.

 

[marco67]

That guy is full of it. The fact that its on RC is of course no surprise.

To add up the flow from your powerheads and Tunze's within a tank and use that to compute your turnover rate is dead wrong. You can't do that. Turnover rate only works for volume entering/exiting a tank.

Matt

Just to clarify;
That's not a direct quote from any one guy, it's more like a paraphrase from a what seems to be a rash of misunderstanding. It was starting to bother me so that's why I posted.

 

[RichConley]

With those high flows, they usually are talking about in-tank flow, and not really turnover. Its a confusion in terms. Theres not really a clear concensus as to what each term means though....

 

[ScooterNH]

Clarification

OK, The water has been exported to your sump and then what?
went right back to your tank and has not been processed by anything!!

OK, I admit I'm new, but I'm really trying to figure this out too. Want to make sure my tank has an acceptable setup.

My new tank is a 90g with a 55g sump/refug. (Not at home right now so can't provide any specs on the return pump). The only filtration I have is LR, and DSB in both the display and refugium (and macroalgae in the fuge). So basically I have the above quoted situation.

But my general question is : Is high turnover absolutely necessary for this type of set up or is this discussion for other filtration methods?

Seems that while I want to have turnover from the display to the sump/fuge and back, I'd want it to be at a rate that allows the biological processes in the sand and LR to do their business. Since I have LR and DSB in both, the main benefit of the sump/fuge is more water volume, and passing through the macroalgae in the refugium. Should turnover here be 10x? 5x? 2x? Just looking for some pointers.

What's the best way to measure turnover/flow anyway? I'd imagine that if I took the hose from the main tank overflow, and timed how fast it fills a 5g bucket, that would then allow me to calculate my overall turnover pretty easily. Regardless of what my pump ratings claim. that make sense?

Thanks

 

[Matt L.]

...Theres not really a clear concensus as to what each term means though....

Each term is actually perfectly clear and has one and only one meaning -- problems with those terms arise from people*.

Matt

* not saying anyone here does that. Just in general. And really, they are hard concepts.

 

[Matt L.]

Should turnover here be 10x? 5x? 2x? Just looking for some pointers.

Okay, here's the answer from a trained hydraulics person: Forget turnover completely.

Just forget it. Start adding powerheads and flow to your tank until the results are desirable. Then stick with that and adjust as necessary. That's all these is too it.

If you have a 90gal tank, the overflow is rated at 600gph, so make sure your pump doesn't exceed the capacity of the overflow. From people with 90's (such as me), you'll probably want more flow, so start adding powerheads, et cetera until you get the desired effect and forget the numbers.

Matt

 

[Liam]

Okay, here's the answer from a trained hydraulics person: Forget turnover completely.

Just forget it. Start adding powerheads and flow to your tank until the results are desirable. Then stick with that and adjust as necessary. That's all these is too it.

If you have a 90gal tank, the overflow is rated at 600gph, so make sure your pump doesn't exceed the capacity of the overflow. From people with 90's (such as me), you'll probably want more flow, so start adding powerheads, et cetera until you get the desired effect and forget the numbers.

Matt

well said

 

[Greg Hiller]

FWIW,

I don't see turn over rate being all that important. I personally think that flow IN the tank is much more important. Also, as you all know, I'm a cheap #$^$ard and creating flow INSIDE the tank typically costs a lot less in terms of electricity. For me, with a sump in the basement I have to work against gravity, which costs a lot. Pumps run 24/7, and end up being a significant amount of the electicity used by a tank.

 

[Scuba_Dave]

Well, my new pump is here - 1200gph, maybe 900gph from the basement
If it doesn't work the way I want I'm going to blame you all
and if it does I will take all the credit

Rainy/cool weekend - so maybe the sump goes in this weekend
I need to make some water

 

[NeO]

I hope along with the pump you got some extra Flow for your tank too, something like couple tunze 6100s
And BTW, I will take the credit and if doesn't work It all your fault from listened to us

 

[ScooterNH]

Thanks for clarification

Okay, here's the answer from a trained hydraulics person: Forget turnover completely.

Just forget it. Start adding powerheads and flow to your tank until the results are desirable...
Matt

OK, that makes sense to me. Thanks for the pointer. I just couldn't see the huge advantage of swapping water (very quickly) between the tanks. Seems like the current pump and overflow provide reasonable enough exchange between the two.

 

[Matt L.]

OK, that makes sense to me. Thanks for the pointer.

You're welcome.

I just couldn't see the huge advantage of swapping water (very quickly) between the tanks.

Not only isn't there any, but chances are, your overflow won't permit it.

It is my personal opinion that people have made a "thing" out of flow and turnover rate, trying to aim for some specific number.

Remember, there are two ways to generate flow in a tank that has a sump. One is to take water from the sump and pump it into the tank. The other way is to generate water movement in the tank with poweheads.

My advice is to consider yourself bound by two points. On the low end, you have too little flow. On the high end, you have too much flow, which means at the very worst, water's gonna come flying out of your tank.

What you want to do is set the flow from the sump as high as possible. This probably won't be to your liking, so start adding powerheads on after that.

How high is too high for the pump to the tank? Thankfully, the overflows in commercial tanks are rated for a specific flow. So all you do is set the flow from the sump to just under the overflow rating. An AGA overflow is rated at 600gph (each). You'll see that 600gph will keep everything alive, but make the water look a little stationary. So start adding powerheads on after that,

The bare minimum amount of water movement you need to for the surface to be agitated with ripples. That means you're getting enough oxygen exchange.

Matt

 

[Scuba_Dave]

I have never gone for a specific figure. But what I have found, is that approx 25x flow in the tank - varied - seems to prevent algae from growing
Right now I have around 24x, but it is not varied enough to prevent dead spots
The new pump will provide 900gph
The existing Tunze give me 1850gph controllable
A 2nd Tunze PH will give me another 1650gph
So a total of 4400gph = 35x turnover for the 125g
Once I swap in the 180g that will drop to 24x
Then I will upgrade the 6000 Tunze to a 6100, possible adding a 2nd 6100 at the same time
If I was closer to the reality of doing this I might purchase the pair of 6000's for sale.

 

[MarkO]

I'm glad there are other cheap #$^$ard's besides Dong and myself
I use a mag 7 which supposedly pushes about 450 gph back into the 150.
My main flow is produced by a Tunze pump which operates at something like 15 W.
I'd rather spend use electricity to light my tank, and the heat generated by the lights keeps my tank nice and warm.... no need for a heater .

 

[Yaktop]

always wondered how much flow actually was running through the pipes with head loss and over time. is there a cheap reliable flow meter we could hook up, monitor, record, and know the reality of it all?

 

[Scuba_Dave]

I'm glad there are other cheap #$^$ard's besides Dong and myself
I use a mag 7 which supposedly pushes about 450 gph back into the 150.
My main flow is produced by a Tunze pump which operates at something like 15 W.
I'd rather spend use electricity to light my tank, and the heat generated by the lights keeps my tank nice and warm.... no need for a heater .

That is the main reason I started looking at a different pump. The new one + the 2nd Tunze will use less then 1/2 the power of my Iwaki

 

[RobboT]

always wondered how much flow actually was running through the pipes with head loss and over time. is there a cheap reliable flow meter we could hook up, monitor, record, and know the reality of it all?

Yes its called a 5 gallon bucket and stopwatch
Seriously, thats how I would do it because true flow meters that dont need calibration and that dont require an engineering degree to read arent cheap. Of course you could always get one of the cheap ones and bribe an engineer with beer and frags to come read it for you

Most people have reasonable access to their drain lines so the 5g bucket and stopwatch method isnt all that crazy. I've done it in the past on my old tank. I used a 1g plastic pitcher though.

 

[Biotoper]

Newb here - I've never understood the idea of keeping turnover low to "give your LR/DSB/fuge/etc time to do its thing." As long as you don't have dead spots in the sump or display caused by very low flow and/or turnover, won't the tank and sump equilibrate in concentration of nutrients/elements/etc? In theory, under the same total system nutrient concentrations, a high turnover system should have better nutrient decomposition/uptake than a low turnover system, because the LR/DSB/macros can't create local nutrient depleted zones around them.

The only benefit I can think of a low turnover system is that you essentially want to create a nutrient poor display and nutrient rich sump by turning the sump into a sediment trap. However, my understanding is that most people, even the lower turnover promoters, want to keep sediment water-borne for skimming. But, then again, I've seen people with skimmers in their first sump chamber (more in line with a high turnover system), and others with it in-line after the sump (more in line with a low turnover system), so maybe people are doing different sump strategies.

All that said, I'm also a cheap b@$tard and putting a small return pump (~300gph after 3'head) in my new setup (20g display, 30g sump), with probably a maxijet 400 mod for display flow.

Ryan