Can you have too little turnover through the sump?

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#2
Are you looking for scientific answers with the philosophy to back them? Or in general and personal philosophy of what one thinks?

I'll go first. Personal philosophy with absolutely no factual basis that I know of but the reasoning of my thought.
As we know the sump is where filtration takes place. Flow through it I would think depends solely on what type of filtration you use. Filter socks and pads don't care how fast water moves through them as long as it does. Does the skimmer care? It might, that's why they make recirculating skimmers to prolong chamber action. But then you don't see them used all that much. Most are concerned with bubble size and or have made single pump, inlet and outlet more effective making recirculated not worth the extra pump and power.

The next most popular filter is macro algae. Is contact time the consideration or is flow actually the desire. I've read where it requires good flow but also that it grows just as good in stagnant water. And have seen it do well in both.

Reaction chamber filtration requires contact and appears that slow tumbling of the products is the norm and requirement. So is trying to get all the water in the display to the sump the goal as quick and often as possible or slow and steady but at least make sure it gets there?

Liquid Bio/chemical shouldn't matter at all and I would think added to the return section would be most effective as a mixing station via return pump then straight to display.

I sometimes ponder how of the display actually makes it to the sump. I have a standard 45 gallon with peninsula overflow which I dislike. I run a Jebao wp25 on else half way down tank behind overflow pointed at opposite end of tank and a Current something (450gph)at other end pointed towards front and towards overflow along with my return doing about 500 gph. I watch floating debris flow up the side of the overflow just to curl away in the last couple of inches of it and head back to the other end of the tank which makes me think I have too much flow in my display that deflects water actually making it to my sump. Thus my Cyano problem thinking my tank is just swirling the dirty water around within the display and I possibly don't have enough somethings to consume nutrients not being exported.

So in thinking. Do we really know how much of our display makes it to the sump? Sure I'm running about 10 times my tanks volume an hour through my sump based on my return pump and head pressure calculations. But, in that hour, what's the actual percentage of display water going through the sump and not just swirling about off the four walls of the tank?

So there you have it. What I ponder staring at my setup looking my system with cabinet doors open watching things tick, or don't tick. One conclusion I have is in the last about 13 years and three or four setups I've had. Never can run them the same. They seem to be trully their own ecosystems we need to dial them in individually based on rock, sand, inhabitants and how many.

My two cents. Alloy. Not even real copper.
 

solitude127

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#3
[MENTION=3281]sklywag[/MENTION] great explanation. I wonder where the baseline of having a minimum of 5x turnover through the sump came from
 

SJacob164

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#4
Well if you are growing any kind of macro algae in your sump or have an algae scrubber I've found the more turnover the better if you want to export a lot of nutrients. Since your sump is basically competing for nutrients with your main display.
 

reefes pieces

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#5
I think there are too many factors in a reef tank and sump environment where proper flow rate can't be calculated. Down to sump design, sump size, water volume, skimmer strength, heater, even dosing etc. I think it's an individual case of testing and identifying if there are problems that are actually happening in the sump. Such as refugium issues, skimmer stability, dosed additives not mixing properly, noticeable temp variance/fluctuations from sump to display.
 
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#6
Excellent response [MENTION=3281]sklywag[/MENTION]. The only other thing I could add is that many of us use biomedia in the sump now rather than live rock. Biomedia requires low flow to establish anaeorbic bacteria growth. Like he also said, every single tank is different. So what you keep in the tank will also determine how much turnover your tank can actually handle. In a tank full of softies with lots of shrooms, low flow is a must. But as far as the sump, I think to some degree low flow is actually better for overall contact time and biomedia.
 
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#7
The definition of a sump in the scope of a plumbed circulating system is a pit or reservoir serving as a drain or receptacle for liquids: such as. a : cesspool. b : a pit at the lowest point in a circulating or drainage system (such as the oil-circulating system of an internal combustion engine). This is not to be confused with a filter, which separates things out, and does not necessarily require a sump or vice versa.

The first sump I saw was on a freshwater tank and fed from a bottom drain, so it had to be a closed system to prevent completely draining the tank. When aquarists started feeding from an overflow and it became an open system, then the question of how fast to overflow (over fill and drain) the DT from the open sump. So if you have a 100g DT and 20 gallon sump and flow very fast through the sump like 5x (500 gallons per hour through the 20 gallon sump, or more like the sump will be pumped into the DT 25x per hour, or every 2.4 minutes) the sump will be doing its main job of supporting the tank volume. If you go too slow then the sump may not be refilling the DT fast enough to be useful- in other words DT conditions (water level, temp, salinity, oxygenation) might change that the sump is not helping to address. They are more like 2 separate tanks than 1 DT and all its supporting tanks.

At that point, why bother with an overflow-sump setup when all those above listed filters can actually be done straight out of the DT. For example: auto top off straight into the DT, hang on back skimmer, above the tank refugium, closed loop circulation, etc.
 
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#8
The definition of a sump in the scope of a plumbed circulating system is a pit or reservoir serving as a drain or receptacle for liquids: such as. a : cesspool. b : a pit at the lowest point in a circulating or drainage system (such as the oil-circulating system of an internal combustion engine). This is not to be confused with a filter, which separates things out, and does not necessarily require a sump or vice versa.

The first sump I saw was on a freshwater tank and fed from a bottom drain, so it had to be a closed system to prevent completely draining the tank. When aquarists started feeding from an overflow and it became an open system, then the question of how fast to overflow (over fill and drain) the DT from the open sump. So if you have a 100g DT and 20 gallon sump and flow very fast through the sump like 5x (500 gallons per hour through the 20 gallon sump, or more like the sump will be pumped into the DT 25x per hour, or every 2.4 minutes) the sump will be doing its main job of supporting the tank volume. If you go too slow then the sump may not be refilling the DT fast enough to be useful- in other words DT conditions (water level, temp, salinity, oxygenation) might change that the sump is not helping to address. They are more like 2 separate tanks than 1 DT and all its supporting tanks.

At that point, why bother with an overflow-sump setup when all those above listed filters can actually be done straight out of the DT. For example: auto top off straight into the DT, hang on back skimmer, above the tank refugium, closed loop circulation, etc.
The reason of a sump is purely esthetics. No one wants to see equipment if the don't have to. The migration from HOB filters with limited size to cannisters adding to capacity with just two tubes in tank to sumps being like much larger cannister filters handling much larger filtration was natural progression. Like lights going from full hoods to being pendants.

Water level is based on the overflow hieght. The speed of return only changes that by a 1/2 inch at best in most tanks. Temperature in display is really correspondent with lighting I think thus the LED change for displays. Although I think smaller wattage heaters could be used if they were in the display and not in sump trying to warm water speeding by it so they run more continually. Just like too big a pump on a chiller not giving adequate contact time inside chiller to work efficiently.

Salt creep is salt creep. That's going to happen more where water tends to be where it isn't suppose to be. Splashing sumps where the large droplets dry out or condensation because of too much moisture because of too many fizzies as I call them. Micro bubbles popping on the surface. You'd be amazed at actually how high those little tiny bubbles are reaching when they do pop.

Oxygen in our systems I don't think is a problem. With the overflow and skimmers I think our systems get planety of it. Even at low flow.

Again I think turn over in sump is based on filtration technique being used. Lots of examples of different techniques and methods of keeping both with fast flow, low flow, no flow(sumpless), chemical, mechanical. My question is and it may actually be simple but not to me. How can we know just how much of display recirculates in an hour through our sumps like when I said. I watch the same piece of debris swirl about my display from top to bottom and side to side for a good ten minutes or so never making it to the overflow. Oh it does, just to zip away before going into it. All the while every fish in the tank tries to eat it and spits it out. They get it, but not the overflow. Which brings up coast to coast overflows to maximise chances of getting all display water to the sump.
 
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#10
Thank you sir :)

A sump in its purest form buffers the volume of the main tank (DT).

Most reef filtration is biological: live rock, sand, algae.

Hybrid sumps (filter sumps, refugium sumps) are a form of remote filtration. And increase ease of maintenance. Difficult maintenance is the 3rd most common reason for quitting (after cost and killing everything).

If it were only for aethestics, an all-in-one hides the equipment just as well but without risk of leaks.

All the filtration methods you listed have optimum preformance flow rates that differ. If you had a separate above the tank fuge that got unprocessed deep tank water that would be best. The skimmer would receive the top film of water very slowly. Filter socks ideally would span half the DT with a wide surface area. LR & LS would be done remotely and slowly so they could be anaerobic, then dumped and replaced new when their pores fill, etc. so that thing below your tank you call the sump is more a remote workstation. Most of the LFS i see have a pure sump because they loose a lot of water during bagging.
 
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#11
How much DT water gets the sump is a complex question. In most cases the over flow drain is at the top, but the return is also at the top, so you are re-draining a lot of what you just pumped in. How much deep water gets to the overflow would depend on how much flow you have inside the tank. Then there are rock that block flow & different types of flow like laminar (right out of the powerhead), turbulent (collisions), and oscillating (wave boxes), just to name a few; and then all those fancy pump flow modes. You would have to do a dye flow study in each individual tank.
 
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#12
Unless one points their return at their oveflow. Returned water isn't just going back to sump. This is or can be observed when feeding as some place the food at the outlet to blast food throughout tank or in return section to acheive the same effect through the return pump itself.

Dye test wouldn't work. The moment dye hit the water the whole system would be effected in seconds before ever seeing a pattern. Would have to be two non mixing fluids like oil and vinegar. That would be sort of neat like a giant lava lamp if you're old enough to remember those.

Anyway, back to Mikes topic and my personal opinion as originally posted. I think even at a very low flow through sump would be beneficial. That's obvious. What matters as all have stated is TYPE of filtration being utilized and "required" contact time or "amount" of water making contact. I would think those running reactors would want a sump designed with as many chambers as they have reactors with the water having to pass through each individual chamber in sequence instead of manifolding a return pump pushing only a certain amount of water through them that flows through sump or if they run individual pumps for each sucking in water as it passively passes by. Even in sump skimmers are collecting what they can as water passes by. Some and I don't know if they still do or not run overflow fed skimmers where all the water enters the skimmers. When I ran ATS I ran them straight on the overflow where all the water had to run over the ATS screen instead of a supplemental pump to run it which in my mind is unneccesary.

We all know that if you run a sock or have a sump designed for filter pads all the water through the sump HAS to flow through them. Overflow water falls into sock, 100%. Those running pads don't put a 4" pad in an 8" space. They put a pad that fits the whole space, 100%. So even the slowest of flows through the sump is beneficial. If all other types of filtration were as effective as these two, maximum effective water treatment would be happening. Even at low flow.
 
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#13
again, my main point is a real sump is all just water and nothing else in it, and its main job is to help maintain the water volume of the DT. so the faster your sump pump refills the DT, the better it is doing its job.

my second point is that filtration can be discussed completely without using the word "sump." as filtration took place centuries before aquariums used a sump.

so when you combine a sump, overflow and filter it gets complicated. your return pump is returning all this good stuff to the DT, such as pods, treated, heated, 1.026 saltwater and top off pure H20, etc. all this goodness theoretically mixes in the DT (eventually), and the incoming volume pushes out dirty DT water back into the filter sump to be processed. so you want it fast in to the DT but slow out of the DT all from the same pump? how?

during power failures you see just how dependent the DT is on the equipment in the sump. the DT temp & O2 levels drops quickly. when the power comes back on, you cant get that sump water recirculating in the DT fast enough.

i used to have 2 apexes: one on my DT, and one for the filter sump (I had a 3rd on my fuge/mixing station too, LOL). so I monitored temp, pH, ORP in each. I was surprised to see the sump was different in all parameters than the DT. I even switched probes and the reading were different, consistently. The sump temp was 1-2' colder during the day and 1-2' warmer during lights out, the pH was always lower especially when the DT lights were on, the ORP was like 100 lower than the DT. I considered that bad, since the goal was to maintain DT stability. The only way I could get sump parameters as close as possible to the DT was to run a very high flow sump, like 4000 g/hr (20x turnover). as sklywag states above, that rate was not compatible with filtration or a fuge, so I setup above the tank fuge and external recirculating skimmer. I stopped compromising and ran each supporting tank optimally as I could.
 

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