The SUMP SLOW DOWN: The benefits of slowing down the water?

Do you think that slowing down the water through your sump benefits the chemistry of your tank?

  • Yes (tell us what in the thread)

    Votes: 96 19.3%
  • No (why do you think that?)

    Votes: 108 21.7%
  • Not sure

    Votes: 281 56.4%
  • Other (please explain)

    Votes: 13 2.6%

  • Total voters
    498

revhtree

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So I have been battling hair algae now for a while! A legit battle! Tons of manual pulling, water changes, tweaks, very conscience feeding, peroxide, clean up crews and much more! The last couple of days I thought about my skimmer, which always seems to be doing a great job. It's not undersized at all but I wondered if I could tweak it a little to get a little more of the gunk out! Which led me to wonder about the water flow moving through the sump, the turnover rate of my systems water, and how slowing it down or speeding it up could make a difference. I can't get any faster right now as I have an Abyzz pump pumping the blood of my aquarium through all it's veins! :)

So what about slower? Could slowing down the water give it more contact time with the skimmer, the algae in the fuge, the carbon etc? So let's talk about the benefits of slowing down the water!

1. Do you think that slowing down the water through your sump benefits the chemistry of your tank?

2. What do you think are some benefits of slowing down the water through your sump?


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Crabs McJones

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I've always had a fast turnover in my sump. The triton method recommends at least 10X and that's what I've always ran with my refugium. Hair algae has always remained minimum.
 

atoll

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With plenty of water movement and lots of live rock in the DT there is no need to turn your sump into a spin drier. One of my most successful tanks had a turnover of once every 3 hours through the sump. Lots of live rock, water movement. Skimmer was also in the sump along with biological media to help keep nitrates in check mainly. This is me about 30 us years ago with said tank.
FB_IMG_1574247596937.jpg
 

dbowman5

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I have a 75 gal DT with a 55 gal tank sump. this features a 15 gal refugium being fed by the partial siphon side of the bean animal overflow. The skimmer section is fed by the full siphon drain throttled down significantly. This provides a slow flow. There is no mechanical filtration. I have detritus settling in the return section (Pump is Hydor Seltz vario AC 2400 at 2/6 flow setting). The skimmer (bubble Magus curve 5) has ample time to interact with the water draining into that section and the varmints in the fuge are getting food direct from the DT. The water is clear, parameters are good, and the flow in the DT is provided by the power heads. This is what i was aiming for. I am watching to see if it will be successful over time.
 
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ReefGeezer

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I don't think it really matters within reason. The only reason I could think of for slowing down flow would be to increase contact time with something like a fuge or skimmer. In doing so, you might possibly extract more nutrients per volume of water processed in a given time. However, you would be processing less water in that same time period. I think it is a wash.
 

snowhite

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The only reason I could think of for slowing down flow would be to increase contact time with something like a fuge or skimmer. In doing so, you might possibly extract more nutrients per volume of water processed in a given time.
That's the answer to his question/inquiry.
 

BZOFIQ

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I always believed and said that you don't have to have a niagara falls effect in your sump, especially the ones with fuge section. Historically I relied on return pump slowly moving water through the sump/fuge and on powerheads in the tank to provide proper water flow. Even with softies I kept the tank water flowing at nearly or over 80x tank volume.

Through the sump, flow was around 6-8x total sump volume and/or about 2-3x tank volume.
 

Neoalchemist

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I want to move the uneaten food and other waste into the filtration quicky. Before it gets stuck somewhere in the display and breaks down.
 

92Miata

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There are a couple things that vary based on flow through the sump - one of the biggest ones is that it changes the cross section of water that moves through your overflows. Higher flow means more mixing, lower flow means a thinner slice and higher percentage of the sort of hydrophobic compounds that skimmers work on.


My favorite tank was a 58 gallon mix reef that I used a maxijet 900 on for a return. It had an enormous 8" bodied skimmer in the sump, about 100gph tank-to-sump turnover, and a pair of old tunzes in the display (3000 gph each?) I used to dump food into that tank, and had a ton of fish, and corals did great.

I started it with about 1000gph turnover with a bigger pump, but eventually came to the conclusion that the huge return pump was just adding additional heat, noise, and electricity.
 

NS Mike D

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I compare it to air cooling units. if the air is flowing too quickly through a cooling coils on a hot day, it's possible for the air to not have sufficient contact time with the cooling coils to remove heat and so you end up blowing warm air back in. Slow the flow, and the longer contact time takes out the heat and now cool air feels great.

IMO, contact time with the the skimmer algae rock etc mean the water flowing back into the DT is devoid of the stuff you want removed. None of the above filtration is 100% instant

This all is premised on being able to test the incoming water against the outgoing, It's all guess work otherwise
 

ReefGeezer

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That's the answer to his question/inquiry.
That's half the answer... Depending on what fuges, skimmers, reactors, and etc. are in the sump, the water leaving a slower flow sump may be "cleaner", but there is less water going through it. For arguments sake, let's assume that the slow flow sump is 100% efficient and a sump with twice as much flow is 50% efficient. So 1X100 <> 2X50. I think the overall "cleanliness" in the system will be roughly the same regardless of flow. I reality, I'm sure there is a flow sweet spot for individual systems, but I think the difference in efficiency would be minor.
 

Wtyson254

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I have about 5-7x total water volume per hour. I also have the output of my UV sterilizer into my drain section of my sumo so the sump get some recirculating flow.
 

jerrod

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To me it’s a matter of finding balance. I have smaller drains then I would like so would actually like more turnover through the sump for filtration/skimming however if the water goes through so fast that there isn’t time for nutrients to be absorbed it’s counter productive. Slowing it down you could have more time in the protein skimmer/reactors but less water being skimmed overall.
 

madweazl

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To me it’s a matter of finding balance. I have smaller drains then I would like so would actually like more turnover through the sump for filtration/skimming however if the water goes through so fast that there isn’t time for nutrients to be absorbed it’s counter productive. Slowing it down you could have more time in the protein skimmer/reactors but less water being skimmed overall.
The water being pulled into your skimmer is dependent on the pump that feeds the skimmer. The flow rate around it wouldnt matter.
 

fishbulb

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Faster flow through the sump should be better, but there's no reason to over do it with Niagra Falls through the overflows.

The idea is that a lot of biological and chemical process depend on a concentration difference. There's lots of examples of this that are analogous to Newton's law of heating and cooler where the rate of heat transfer is proportional to the specific heat of the substance X the temperature difference. So it's faster to heat a gallon of water by 1 degree if the temperature difference between the water and heater is greater.

It's the same thing for many chemical processes as well. A skimmer will have an easier time removing organics if the concentration of organics in the sump is highest. So if the turnover rate in the sump is super slow, then the skimmer will deplete the sump of organics and be less efficient removing the incoming organics from the tank. It's best to equilibrate the concentration of organics with the tank, which would likely mean the higher flow rate.

In practice, I doubt this matters much over the large range of flow rates through the sump we use in our hobby. My guess would be that if the flow rate through your sump is so slow that you can't even keep the tank's temp stable, then turn it up (your are likely not optimally filtering as well). Otherwise, it's probably not a big deal.

Just my 2 cents anyways,
FB
 

vlangel

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My flow through the fuge and sump are relatively slow by today's standards. I am an old salt, (or maybe just old, ha ha!) but I was taught that slower with a fuge is better so nutrient uptake is maximized by the macro algae. My display is a 56 gallon (with 13 fish in it) with a 30 gallon fuge and a 20 gallon cryptic sump with sponges. My flow is only 400 gallons per hour so pretty low at 4Xs turnover. However I have a gyre and a tunze powerhead in the display for probably 20+ Xs in the display with LR and sand. I feed very very heavy and do not run a skimmer and have no nuisance algae except film on the glass that needs cleaned once a week. It's a mixed reef but heavy on LPS and nutrient loving coral plus has ornamental red macro algae.
If I had mostly SPS I would add a skimmer in the sump and still feed heavy and probably increase my water changes a bit. Anyway, slow flow through the sump has always worked for me.
 
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