Sump flow and turnover rating. How is it done?

[Frankie]

Hello everyone,

This is a thread for those that wish to discuss flow rates through a sump. I would like to start a discussion on this topic and start to put together information for the new and long term reefers.

There is no right or wrong in this. Everyones system is different and all have pro's and con's about them.

So share your experience of success/failure and let's all learn something new!

Here is my take on the topic for my new design.

Designing my new system has been interesting this time around. I am figuring in all the factors this time and sump flow is a major concern for me this time. Durning my time building this sump I did a lot of reading on sump flow and pro's and con's to the ratings of that flow.

After finally figuring it all out I realized there may be a lot of you out there that are struggling with the same topic and thought I would get a discussion going on it.

For my current build, contact time is important to me with the skimmer. There is no refugium or algae based filtration so my goal this time is how much water flows through and how much water the skimmer can process out of that flow before returning to the display tank.


One thing I try and keep in mind when designing a sump is "return water is not to be used for display tank flow". It's main purpose is returning the freshly processed water to the display tank.

All flow in the display needs to come from either power heads, closed loops or other means of moving the water.

There is good reason for this. Take my system for instance. The return water is not only being processed in the sump, it is also going through a chiller just prior to returning.

This cooler return water, if returned to fast can cause fluctuations in temperatures in the display if not returned in a gentile, passive way to mix into the DT water.

For my system and method of filtration I am finding that matching the return pumps output to the skimmers flow will be best for my purposes.

My goal this time is to match the two flows. Due to head loss on a return the skimmer pump will need not be as powerful as the return pump. So I have to match head loss on the return with the flow into the skimmer.

This will give me the ability to process in the skimmer as much water as possible that passes through the sump.

I'll stop here for now and open it up to discussion. I look forward to hearing from all of you and how you did your systems flow.

If your building a new system and would like to talk about the best possible flow rates for your build please share what's on your mind!

Frank

 

[Krish]

Great Topic Frankie!

Here's my take on it...I like to utilize my sump return as part of my flow for my tank. Not so much as a major role, but I like to make sure my return flow atleast handles surface aggitation that way I don't have to use another pump to do it. I've never had a really big tank, so my sump returns have always been suitable enough to provide this for me. 700 gph return in a 75 gal worked great through a sea-swirl and 950 gph ( minus headloss through a chiller and back up to the tank) gave me what I needed for my 38 gal. Some like the slower flow through the sump as they say it gives the skimmer more time to process in-coming water while on the other hand, some say more flow, and more water passes through the sump each hour so more water can be processed so it's no differece LOL! I've honestly never noticed a difference either way for me personally. I run high flow rates in my tanks, run bare bottom tanks, use liverock as primary means of filtration, a skimmer and phosban reactor and regular tank maintenance. They have all treated me well on different sized tanks with different levels of flow rate through the sump. When refugiums come into play, then I can see flow rate being more important. Some algaes require alot of flow and others, maybe a lot less. Sometimes, it will drive you nuts trying to figure out the exact flow rate to go with

This cooler return water, if returned to fast can cause fluctuations in temperatures in the display if not returned in a gentile, passive way to mix into the DT water

I have a question on this comment though Frankie...Wouldn't the fact that all this volume of water being in a closed system mean that whether the water is returned fast or slow to the display tank, all of the water in the tank should be the same temperature everywhere being in a closed system? Just a thought...I'm thinking if the chiller will shut off when the temp is within range and only turn back on when the temp rises to wherever you have it set (usually only allow for a 2-3 degree swing) then whether it is returned to the tank fast or slow, the temp pretty much everywhere in this closed system should always be exactly the same minus point something of a degree coming directly out of the chiller versus maybe somewhere at the very bottom of the display tank which would be nothing much of a concern or...Should I go back to bed and re-think this :lol:. I'm thinking it shouldn't cause a major concern in the same way as a heater being used in a tank. Whether placed in the sump or in the tank, water temp in these closed systems should be pretty much the same everywhere. Any variation in temp degree should be so slight (as in right next to the heater vs the other side of the tank) that it wouldn't cause much of a concern. Just a thought...Thinking out loud and adding to the discussion. Great topic again. Should be a good one

 

[Frankie]

Good question krish about the chiller.

I run MH's so the surface area of the DT will be warmer then the lower levels right? That water is being pulled off and ran through the filtration and then to the chiller prior to returning. I try to keep my aquariums around 76f that I have found to be the ideal temperature for many things (different topic) so the chiller is not off most of the time. The house is set at 77-78f so there is a constant conflict in warming of the water.

Surface agitation mixes that warmer surface water also. The water being pumped back in is actually cooler after it passes through the chiller retuning cooler water means a temperature rise and drop. So the closed system theory is really not true. Were not a closed system imo if the water is exposed to air. (it's just not connected to the ocean )

I'm not worried about a 2 deg. change though. BUt back to the question, the faster the water is moving the more stable the temperature if heaters and chillers are involved right? The slower the water the greater time for change.

Keep it coming buddy, good conversation.

 

[Krish]

Good thoughts and perspectives Frank! I think I stirred the pot enough to send this thread in a few directions and so I'll give others a chance to chime in before I add any more feedback.

 

[Krish]

Ok...Maybe I'll just add one more small thing . Unless your tank is custom built, if you buy a reef ready all-glass tank/Aqueon tank, their overflows are usually only rated at 600gph per overflow if I remember correctly. So on a 125 gal tank which has dual overflows, you could only run a 1200gph return pump which runs the overflows pretty much maxed out. Does this account for anything as in do you think they designed them this way going by some formula which calculates how much flow should pass through a sump given the tank size or did they just say "Hmmm...600 gph per overflow should do the trick"??

Something else to think of.

 

[Skimmy]

as most people know, I am a fan of slow flow through the sump.
I would say a good rule of thumb is to figure out the gph processing of all the filtration devices(skimmer/media reactors/etc),
and not provide the sump with more flow than that, I also use the 3-5 times an hour turn over rule.
mechanical filtration like socks and pads are the only thing that benifit from providing more flow than the sump filters can process.
but, on the flip side more flow through the sump is not going to hurt anything, your just going to use more power and possibly have more salt spray in the sump with faster flow.

 

[Peppie]

So pretty much in a nutshell, if you run more water to the skimmer section of a sump than the skimmer pump is rated for you are not getting the most out of your skimmer?
Say you T off your overflow, one to the skimmer and one to the fuge. Would this be better for the fuge (cheato) to filter water straight from the DT? Or should it be ran thru the skimmer before it is T ed to he fuge? I think this would throw a wrench in the flow volume of the entire sump.
Would it not be better for the fuge to have a very slow rate of turnover so that the macro alg. has more contact time with the water? Or is that really an issue? Even if the water is moving faster it is still in contact with the macro alg,
My next system does not have a sump. It does have a fuge area that will contain macro algae, and a possible dark space for some sponges. So do I move the water thru there at 160gph or at 320gph ? Total vol. of the tank is 85gal.

Just my 2 cents on the return flow for water movement. I would rather find the correct amount to run thru the sump for max filtration of the equipment involved, and base my return pump on those figures. Then keep the return lines close to the surface. One reason for the surface agitation and the other for less water siphons back to the sump when the power goes out. I would run power heads to rely on the DT water circulation.

Another 2 cents on the cooler water entering the tank. IMO the temp in the whole system is so close that you would be splitting hairs on how fast the water was returned to the DT. Most hobbiest would not even think of this let alone try to compensate for it. IMO

Good read so far. Got me thinking an wondering if I should change my flow rate.

 

[eww]

Great topic Frankie. I love these discussions as they bring out all the great ideas and experiences of all the experienced and not-so-experience reefers here.

IMO the skimmer is going to process the amount of water it is supposed to no matter how fast the water flows past it. Say you have a 100 gal system. If you have a skimmer that process 300 gal/hr and you are running 300 gal/hr past it or 950 gal/hr past it the skimmer still processes 300 gal/hr right? Granted the faster rate would not catch all the water, i.e. there would essentially be 650 gal/hr that did not get processed in my high flow example. Still the entire water column would be processed 3 times an hour by said skimmer and that seems quite enough in my book... but my book is not that thick yet .

On the macros in the fuge... Again IMO it doesn't seem like it would matter as the macros are submerged entirely in the water column so it seems like it wouldn't matter how fast the water flows past or through them. They are still absorbing nutrients at the same rate regardless of how fast the water is moving right??? It's not like the macros have to hunt and stalk their food source to catch it. It just surrounds them at all times and they take what they need when they need it.

We currently have a system that goes by the 3-5x the volume rule for the sump flow past the skimmer, through the fuge with macros and out the return. It is thriving and the macros grow like weeds. There are tons of pods and critters living in there as well that grew and reproduced there naturally. We have not bought any and added them. That being said we have seen several beautiful tanks that run more like 8-10x the flow vs. volume and they are also thriving, beautiful systems.

Therefore it is my opinion that the flow rate doesn't really matter as much as a lot of people like to make it sounds like it does. It seems that as long as you have flow and not stagnant water all will balance itself out and run well in the long run and that what we all really want right?

As to the chiller discussion I don't have much to add there except in concept it seems a lot like the air conditioner in your car. You turn it on when it gets too warm in the car and it lowers the temperature to a comfy level of your choice and keeps it there if you are fortunate enough to have a nicer car with a thermostatically controlled system. I have not noticed a big swing of cool vs. hot air once the desired temperature is reached. The air in the car is warmed by the bodies in the car and the outside environment and pulled back in to the system, cooled and returned to the car interior. Seems it would be much the same in our tanks. Again, no first hand experience here with a chiller at all. I'm just thinking with what I hope is common sense. Not sure if it is though

I'm not sure if this is .02 or .04 worth or not but there it is anyway...

Eric

 

[Krish]

Great points!! On the fuge you mentioned Eric, sometimes depending on what algae is in there would determine how fast you should have your flow rate passing through it and here's an example why. Take a ball of chaeto in there for eg. It is argued that the chaeto works better for you if it is tumbling. I think the reason behind it is as it spins all sides of it gets exposed to the light so it grows better vs it sitting in one spot and only the top receiving light. Not sure how true it is as I've never used chaeto, but that is just what I've read about it over the years.


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[mfinn]

as most people know, I am a fan of slow flow through the sump.
I would say a good rule of thumb is to figure out the gph processing of all the filtration devices(skimmer/media reactors/etc),
and not provide the sump with more flow than that, I also use the 3-5 times an hour turn over rule.
mechanical filtration like socks and pads are the only thing that benifit from providing more flow than the sump filters can process.
but, on the flip side more flow through the sump is not going to hurt anything, your just going to use more power and possibly have more salt spray in the sump with faster flow.

I'm in the slow flow camp as well.
For me, it just works.
I use to push the envelope on what my overflows could handle just to eek out a few more gph back to the DT, but seemed to run into a few problems.
One was a tendency to end up with micro bubbles in the display tank. Another was random floods, ( almost always when I was out of town) when one of the drains became clogged, with algae or a snail or a fish, etc. All of which were my fault.
Then there is the contact time with filter media and equipment.
I just seemed to find I liked how everything worked with a slower flow.

 

[mojoreef]

Well this is one a person could write a book on, lol and to be honest it really depends on what the system is and what the user has in mind. So for that their is no real carved in stone right way of doing it. If one wnat to get technical then you got to go peice by peice. So heres a rough stab at that.

> Refugium: Biological system that needs contact time and fallout in order to operate properly. If you have water running to fast over the sand you will loose an amount of the detritus fallout and you risk just making it a nitrate producer. Most algaes like it slow for contact time and absorbsion, some dont mind it quick as they have evolved to handle high flows. So bottom line is slow to medium, which can be a bit of a bear when other things in the sump like it a little quicker. Solve?? branch it off in the sump somewhere and allow it to return down the line somewhere, also you want the water entering it to be straight out of the tank, that way it has the most detritus in it and that will feed it.

> Skimmers: Skimmers follow rules and laws ( See here http://www.reeffrontiers.com/forums/f14/skimming-numbers-59522/ ) and every skimmer is different as to how it gets the job done. Personally I like it slow, but thats a debate for another day. As with all equipment it flows the basic law of flow rate, which is Hours = 9.2 purity coefficient. Which is a fancy formula that tells you how many times the water in the tank must flow through the peice of equipment in order for all the water in the system to have been treated. So bottom line is that you dail in your skimmer to make it work the way it was designed and then place it in the sump at what ever position it needs to be in, in order for it to do its job. For me I take the water right out of the drain (first sump compartment) and treat it.

>Chillers are rated at a certain flow that allows them to work effectively, so you set it with a lfow that is determined by the manufacturer, usually its pretty slow in order to be effective.

>Ozone happens inside the skimmer and then off gasses as it comes out, for me I have it run through a compartment of gac which removes what ever is left behind by the off gassing.

> heaters, effluents and so on are preety much place it where you cans.

So normally if a tank has all these peices of equipment, the system usually does not need to rely on the sump return for added flow, its simply a place to treat water and return it. If its a small system then it might need the return as flow, so ok but keep in mind what you are trying to do in the sump. For me I have found that it is best to skim the water of the surface of the tank, this way I get the hottest water and the various oils and so on off the top. In order to do that I have a coast to coast overflow and I designed my water flow to direct detritus and so on to the top water. I return it down as low as I can get so that the tank is turning over as much raw water as posible, but you can also do this by having return and drain on opposite sides of the tank.

The main conflict in a sump is for those that want and use biological (refugium) and equipment (skimmers/ozone/and so on) in their sumps. The best methods are where you seperate those two systems with in the sump so that you can have control over the flow that goes into them, So skimmer and refugium would be in first place in the sump and taking the rawest water and then sending their effluent down the line, so sperate compartments where you can adjust the water with a valve that is entering the refugium.

Again its not really something you have to be perfect in as the flow rate rule above states it will all eventualy get treated at some point. But for those that want you can try your best to dial it in.

Mojo

 

[akunochi]

So I am basically a 8-10x per hour guy of the volume of the DT only. I feed that into a skimmer section with a separate feed going into a ATS and fuge. This can be dialed back. I also tend to over rate my return pump so I can feed a media reactor or etc etc with the pump via a manifold. So after all is said and done I end up with about 7x turnover throughout the sump.

 

[thatguy559]

Ok...Maybe I'll just add one more small thing . Unless your tank is custom built, if you buy a reef ready all-glass tank/Aqueon tank, their overflows are usually only rated at 600gph per overflow if I remember correctly. So on a 125 gal tank which has dual overflows, you could only run a 1200gph return pump which runs the overflows pretty much maxed out. Does this account for anything as in do you think they designed them this way going by some formula which calculates how much flow should pass through a sump given the tank size or did they just say "Hmmm...600 gph per overflow should do the trick"??

Something else to think of.

i have a 120g aga and i use all four holes in my overflow as drains and i have a reeflo dart open full blast. so max is not 1200gph

 

[Krish]

i have a 120g aga and i use all four holes in my overflow as drains and i have a reeflo dart open full blast. so max is not 1200gph

Lucky you !! eace: From what I can remember, they rate them at 600 gph per overflow. This is probably the amount of flow they suggest to avoid any potential issues. This doesn't mean they can't handle more. We sell Orion XTR amps for eg that are rated at 500w rms (in the manual). The certificate that came with one of the amps says it tested at 580 watts rms. Same thing with the subs. The XTRPRO 12 inch rated at 500 watts rms and we put 700 watts rms into it with no problem and I know it can take more so the 600gph per overflow I mentioned is just what they rate them at probably to protect their butts and to be on the safe side.

 

[Krish]

Just for an FYI, here a link where you can read it. Page 8
http://www.aqueonproducts.com/assets/012/23815.pdf


Download the file...They rate the mega flow overflows at 600 per over flow. Corner overflow are rated at 400 gph. Like I mentioned, it's probably to protect their butts and function properly. I wouldn't recommend anyone exceeding it. If they did and ran into a problem they can't sue the manufacturer or blame anyone but themselves.

MegaFlow™ single molded overflow aquarium.
Overflow: 600 GPH each.
(Gravel not included.)

 

[Scooterman]

i have a 120g aga and i use all four holes in my overflow as drains and i have a reeflo dart open full blast. so max is not 1200gph

We'll your leaving out something there; by design the other two holes were meant for returns not drains so yes you can pump out more through it that way, so yes your not using the manufactures design and able to get more out if it.

 

[Krish]

We'll your leaving out something there; by design the other two holes were meant for returns not drains so yes you can pump out more through it that way, so yes your not using the manufactures design and able to get more out if it.

Exactly! This would be more of a "custom build" as it is not being used as per the manufacturers specifications. Using it as it was designed to be used is what I was talking about which goes along with the point I was trying to make in my post which seemed to have gone completely over "thatguys" head in him trying to prove me wrong I guess. I don't know. The point I was trying to make was all-glass (now aqueon) designs their pre-drilled tanks with their over flows rated at about 600 gph per overflow. Maybe they are trying to tell us something (or know something) with using this particular flow rate on their tanks. Put simply, maybe they are saying slow flow is the way to go (maybe they have a formula to go by...I don't know). I used a 950gph return on a 38gal where they would use a single overflow rated at 600gph on a 110 gal tank. Something to think about...


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[thatguy559]

thats cool and all i have been doing this on their tanks for 5 years now. everything i had on their 210g aga is on my 120g aga same set up and never had an issue. im not arguing with you! didnt go over my head or anything. i love how people can perceive things differently in text rather then talk. this was about high or slow flow through the sump and not proving you wrong im just stating that they rate their overflow using a single 1" drain for the 600gph rate. im using both the 1" and the 3/4" as drains. thus increasing my flow to around 2800gph with the head pressure. i have had always used high flow through my sump. ill put it like this " WHAT WORKS ON ONE PERSONS SYSTEM MAY NOT NECESSARILY WORK ON YOUR SYSTEM" i just do what works for me :yo:

 

[Frankie]

Yeah, if you use the overflow as intended then you have one hole per box for return so 600 is the correct answer as Krish stated . Not that using both holes is breaking the rules or anything, just changes the intended rating is all. Smart move ThatGuy
Good catch Scott!

This thread is getting interesting! Keep it coming. I lean more towards Finn's view really, slow flow is good contact time in the sump area, and that is the best situation really. Plenty of time for the filtration to do it's job.

As for refugium's and such, as Mike stated, not all macro algae needs saturation time, like cheato for example. Other then cheato I cannot think of any algae that dose better in slow flow vrs high flow. I am even skeptical that cheato does better in slow flow. I had a lot of flow running though my old elevated refugium and the cheato grew at a rapid pace. I harvested from that refugium every week to keep it in check. The flow was around 1000 gph on that setup.

A good example of high flow on algae would be the Algae Turf Scrubber method. (ATS)

With ATS the flow is moderately fast and the algae grows quite well. Putting all the hype on this method aside, it is a very good way to lower nutrients in an aquarium.

Personally, I think adding and utilizing algae to harvest nutrients is pointless. Why would I use something that I am trying so desperately to keep out? Show me one aquarium that is only using macro algae as a means of filtration that is sps dominant. I don't know of any, and if they are out there I can put my money down that the DT is also infested with algae. It's the nature of that beast to be so. If the algae is in the filtration then it will be in the DT. Right?

Look forward to more! Keep it coming friends, the topic is starting to get a bit deeper now

Frank

 

[Krish]

thats cool and all i have been doing this on their tanks for 5 years now. everything i had on their 210g aga is on my 120g aga same set up and never had an issue. im not arguing with you! didnt go over my head or anything. i love how people can perceive things differently in text rather then talk. this was about high or slow flow through the sump and not proving you wrong im just stating that they rate their overflow using a single 1" drain for the 600gph rate. im using both the 1" and the 3/4" as drains. thus increasing my flow to around 2800gph with the head pressure. i have had always used high flow through my sump. ill put it like this " WHAT WORKS ON ONE PERSONS SYSTEM MAY NOT NECESSARILY WORK ON YOUR SYSTEM" i just do what works for me :yo:

Actually you didn't understand my post. I said...

.... Unless your tank is custom built, if you buy a reef ready all-glass tank/Aqueon tank, their overflows are usually only rated at 600gph per overflow if I remember correctly. So on a 125 gal tank which has dual overflows, you could only run a 1200gph return pump which runs the overflows pretty much maxed out. Does this account for anything as in do you think they designed them this way going by some formula which calculates how much flow should pass through a sump given the tank size or did they just say "Hmmm...600 gph per overflow should do the trick"??Something else to think of.

And you say...

i have a 120g aga and i use all four holes in my overflow as drains and i have a reeflo dart open full blast. so max is not 1200gph

You didn't answer the question here. I know a reef ready All-Glass tank can handle more flow than what the manufacturer rates them at. Pretty much everyone knows that. The point I was trying to make was do they rate them this low for a reason? Are they trying to tell us something? You totally disregarded that part and just pointed out that 1200 gph isn't max for dual AGA overflows which wasn't the question so I can only take that one way. I made a point to add to the discussion which was pushed aside.

In any event, I agree with you. Go with what works best for you. I tell people that everyday here that what works for one person might not work for another so do what suits you best. I ran high flow sumps and low flow sumps. Both were a success for me so really it can go either way IMO.