Who's got the lowest turnover through their sump?

[TylerS]

I've done a lot of reading which suggests 3 to 5x display tank turnover is a good target for turnover through sump. I can post links if you guys want.

I'm curious who are running their long term successful tanks (2+ years?) on 3x turnover or less?

I'm particularly interested in larger tanks (70 gallons or more?) with a refugium.

 

[James605]

Any reason your shooting for slow as you can in the sump?

 

[Randy Holmes-Farley Verified Community Expert]

I don't think the 3-5 has much basis in real data. Many people run higher and lower rates through the sump. IMO, it depends a bit on what you are doing in the sump, but I do not think the flow needs to be any special value. I've run it much lower than 3x per hour without any apparent issues.

 

[d2mini]

There are plenty of tank over the last decade or more have run that flow rate. But I think that's a kind of old school thinking. My old Ecotech cube that ran for 3-ish years before it was torn down to move was run with 3-4x flow, just because that's all my return pump (eheim 1262) could push.
This number was probably due to noise from older style overflow/drain setups. I think there is also some misguided hypothesis about the skimmer being able to work more efficiently. But I haven't seen any actual studies that show a slower flow rate through the sump is actually beneficial.
With the advent of full siphon setups like beananimal, it blows those number out of the water and can be completely silent.
I'll probably be pushing a minimum of 10x through my new tank. The drain setup will actually give me the ability to push as much as 35x if I wanted to.
Some advantage are better surface skimming for protein removal, detritus suspension, more flow for cheato rotation if you have it, more filtering through socks if you have them, and more flow through the display tank.
The Triton Method (which utilizes a large refugium in the sump) recommends 8-10x.

 

[Retro Reefer]

This is a great topic for debate, I have thought about this for years and it seems that for every positive benefit I can think of there are also negatives that apply to either fast or slow water turnover rates.. In my current nano I'm sticking with the slower flow stock pump that came with my system because I'm running a UV sterilizer inline on my return and it also seems to me that with the limited volume of mechanical and chemical mediums that I can fit in my sump a longer contact time with a slower turnover is a good thing I'm also worried about potential extra heat a larger return pump would generate as I'm already battling temp issues with my BC

 

[d2mini]

This is a great topic for debate, I have thought about this for years and it seems that for every positive benefit I can think of there are also negatives that apply to either fast or slow water turnover rates.. In my current nano I'm sticking with the slower flow stock pump that came with my system because I'm running a UV sterilizer inline on my return and it also seems to me that with the limited volume of mechanical and chemical mediums that I can fit in my sump a longer contact time with a slower turnover is a good thing I'm also worried about potential extra heat a larger return pump would generate as I'm already battling temp issues with my BC

I personally don't think it makes a large difference either way. Do what's right for your setup, in your case, getting the correct amount of flow through your UV.
The whole "contact time" thing I don't believe. If the water passing through your sump never came through again, then yes that would make sense. But in our closed systems that same water will be back through the sump over and over again.
I went from a system that was pushing 3-4x to a larger system that was pushing at least 15x through my sump and I can't say their was a noticeable difference. Two completely different systems though so hard to compare.
But if I was setting up a new system, I'd go for more rather than less due to the advantages I mentioned in my previous post.

 

[mfinn]

I really never thought it was better to run a slower flow ( 3x-5x), I would say that it works better for me.
While I'm still a fan of Sicce, Tunze, and Eheim for return pumps, lately I've found I like the benefits of having a controllable DC return pump.
Gives you the ability to find that sweet spot for flow.

 

[pondman]

Thing is most keep the heaters in the sump.and a slower flow is better for heat transfer.

 

[Randy Holmes-Farley Verified Community Expert]

Thing is most keep the heaters in the sump.and a slower flow is better for heat transfer.

Yes, in a single pass one can warm up cold water more with slower flow, but single pass is not the case here. Higher flow means more passes, so I do not believe slower flow is better for heat transfer. Aside from flow so high and turbulent that there are huge amounts of air entrained in the water so the heater might be exposed to mostly air, there is no reason to think heat transfer is ever more effective at lower flow.

Heat flow depends on the temp difference between the heater and the water, and higher flow only serves to bring the less heated water into contact with the heater faster, so better transfer.

 

[TylerS]

By the way, the reason I'm asking what people are running is because I'm building a basement sump and higher turnover requires much larger and more expensive pumps which also consume more power.

I think there's a point where the turnover rate is good enough, and above that just cost extra money.

The factors I can think of that might determine this rate are:
1. Water parameter consistency between DT and sump (temp, o2 levels, neutrient levels etc.)
2. Ability to get suspended detritus and nutrients through the overflow and into the sump (probably highly variable for everyone's tanks based on in DT turnover from power heads, etc.).
3. Effective use of your skimmer / matching skimmer flow rate. If you need a skimmer that pulls 1000gph then it wouldn't make sense to me to have less than 1000gph through the sump. Here there are also lots of variations per tank...

Just wondering what people are doing.

 

[Retro Reefer]

By the way, the reason I'm asking what people are running is because I'm building a basement sump and higher turnover requires much larger and more expensive pumps which also consume more power.

Another good point to consider, pumps can get expensive to purchase and operate also having a back up pump on hand is a very good idea pushing your total pump cost even higher.

 

[don_chuwish]

Seems to me that it's really all about matching flow rate to the skimmer. We don't use the return nozzles to stir up detritus and create movement - that's what powerbeads are about.