Why do we assume a large return pump is needed?

[Entropy]

Yes you are correct about my EV150. I really don't have a way to test slowing down the flow rate of the tank to sump because as I mentioned it is my only source of flow. I don't think slowing down the flow in my tank would be wise and I do not want to add powerheads or a closed loop at this time so there is not much I can do. I also do not see an effective way to skim the entire surface of the tank easily. I have a corner overflow and there is still an occasional film on the surface on the other side of the tank. I have tried moving my returns around to get the surface to flow towards the overflow, but have still not found a perfect solution. It seems the film has a natural aversion to the overflow although I know that is silly to mention.

It might be worth investigating for someone that has the means though.

 

[Herbert T. Kornfeld]

NOLACLS,
Well, did you check out the two TOTM threads I linked to above? The 320g by DNA with the 100gph overflow is a prime example of what I am talking about. FWIW, maybe its an even better way of running a tank...as how many of you have had your tank's corals go sexual?

Instead of running your chiller on a sump return line (which will forst heat the water as it passes throught the pump, then chill it, and then make alot of back pressure on the pump, making it give off even more heat...) why not run a large closed loop with a high-circulation/low head pump (so you dont need in tank pumps like TUNZE's)? Or, as an alternative, a smaller high pressure pump with flow eductors on the outlets. You could use a wave device like a oceansmotions manifold or actuated ball valve for the closed loop to get your wave action, and run your chiller on the closed loop somewhere. And for the overflow, a smaller pump that will run your overflow at 300gph should be plenty. I bet you will use less watts, your pumps will transfer less heat into the tank, and your tank wont need a seperate room because it sounds like a whirlpool.

 

[NOLACLS]

I did quickly read over those links...im at work so cant really look at it all the way. I will tonight tho. I have never had corals go sexual as far as I have seen or know about. But I am assuming that you mean running the water slower through the sump for more contact time on the skimmer would pull the gunk out before it did damage.

I am going to run a OM 4way on another barracuda...just never thought about putting the chiller on CL. So would you just T off the line, go into the chiller and then back into the line before the OM?

As far as the noise...I am putting the pumps chiller and my ro/di outside. The wall the tank will be on is an exterior wall with vinyl siding on the other side so I am just going to run the lines through the wall. Also my tank is 3' from front to back...I would like enough flow from my sump returns so they can reach the front of the tank. The 4 returns from the OM will be one in each corner. Well that was what I was thinking anyway Maybe I will go down to the dart that only does 3600 @0' and seems to drop off quickly. Then maybe up the barracuda to the hammerhead that does 5600 for the CL and chiller. Does that sounds like a better plan

 

[Herbert T. Kornfeld]

Entropy,
As far as the surface skimming goes, I see you are using an AGARR...I think that is more the source of your problem than the circulation. Everyone I know with those ends up cutting up the overflow because its too restrictive. The slots are too narrow and shallow to break up the surface tension of the water and allow it to be a true overflow. I see everyone dremmeling the top edges, or cutting out every other tooth to make up for this. Trust , me on this... the 125gallon I see every week only uses a hang-on amiracle overflow, but its teeth are better, and the whole tank's surface is clear with just 200gph of flow. That 'natural aversion' to the overflow that you speak of is very true...its because AGA overflows are crap. FWIW, if you were to lower the flow, and block off the lower intakes so that the overflow takes only water from the surface, I think your problem would be solved. Otherwise, when I have ordered RR tanks from AGA, I have them drill the overflows and leave out their baffles...then I make my own to put in...much better results. A you can see from DNA's tank, he only uses 100gph and has no problems keeping the surface clear. As far as someone studying the effects of the low flow on a skimmer...that 125g of my cousins is a prime example. He has to empty out his remora-pro collection cup more than before. He says that before he would empty it once every week...now he has to every 4 days. Only reason I know is because it really throws him off (not just emptying it once every weekend) and so I am making a bigger collection chamber for him to connect it to. He claims that it must skim more because the overflow's water doesnt just speed past the skimmer in the sump and get mixed back into the water (making it more difficult for the skimmer to grab again unless you have a super high flow overflow to compensate, because the proteins that the skimmer can grab the easiest are the ones that have already started to bond with the air at the water's surface...so targeting this part of the tank, and skimming it multiple times to be more complete might work better than having to compensate for unintentionally 'reblending' it into the water and then needing an even bigger skimmer and overflow/sump pump to compensate). Make sense? I hope to test that theory soon. I want to see if running high-flow through the overflow hinders the skimmer's processing abilities...necessitating even more flow and bigger skimmers to compensate (because the water that comes from the surface is bypassing the skimmer and getting blended right back into the water). AND, deltec has based their whole recirculating skimmer line on the idea of lowering the throughput and passing the water through the skimmer mixing pump multiple times. But thats a whole other can of worms...

 

[Herbert T. Kornfeld]

NOLACLS,
"But I am assuming that you mean running the water slower through the sump for more contact time on the skimmer would pull the gunk out before it did damage." is what you said...you lost me...Im not sure what you are referring to here.

As for the OM and the chiller...exactly what I was thinking. You could even use a cannister type pre-filter on it to keep it clean, or heck...as a place to keep your phosguard, carbon, or whatever. From what I remember, darts are better used in low-head pressure applications anyways...so a closed loop is a waaay better idea for that pump anyways. And this way you could turn your sump off (or have it fail) and still have your closed loop (and therefore chiller) running just fine. A closed loop means more reliability from any pump purely based on the fact that it is under less stress from back-pressure.

As far as noise, I wasnt talking about the equipment so much as the noise from running overflows with so much flow. I hate that noise myself....sounds like a toilet in the room...even with a durso its still annoying. I will admit that that was the reason I first started looking into the methods I am talking about now...more flow for less energy cost was my secondary.

 

[Entropy]

I did dremel the oveflow pretty good. My slots are shaved about twice as big and go all the way to the top. I never thought of blocking off the bottom slots. That may be an option but I cannot think of an easy way to do it without removing all my rock.

I guess I can chalk this on up to another "if I had to do over again" issue.

 

[polcat_4u]

hey polcat_4u, what is the wattage of your water movement? How loud is it...or what room is it in?

It's 110 watts total, pretty quiet they are both under my stand. No heat issues.

I hear what you are saying. I choose a becket skimmer that needed a pressure rated pump and decided to match it with the same retun pump. I'm installing an OM squirt (wavemaker) on the two eductors. I am thinking about taking the current return pump and making it a closed loop and just buy a small mag pump for a return. I guess I'm kinda doing what you are talking about but I can see the validity of low flow overflows and sumps.

Mike

 

[NOLACLS]

NOLACLS,
"But I am assuming that you mean running the water slower through the sump for more contact time on the skimmer would pull the gunk out before it did damage." is what you said...you lost me...Im not sure what you are referring to here.

As for the OM and the chiller...exactly what I was thinking. You could even use a cannister type pre-filter on it to keep it clean, or heck...as a place to keep your phosguard, carbon, or whatever. From what I remember, darts are better used in low-head pressure applications anyways...so a closed loop is a waaay better idea for that pump anyways. And this way you could turn your sump off (or have it fail) and still have your closed loop (and therefore chiller) running just fine. A closed loop means more reliability from any pump purely based on the fact that it is under less stress from back-pressure.

As far as noise, I wasnt talking about the equipment so much as the noise from running overflows with so much flow. I hate that noise myself....sounds like a toilet in the room...even with a durso its still annoying. I will admit that that was the reason I first started looking into the methods I am talking about now...more flow for less energy cost was my secondary.

I was referring to when you said something about having corals go sexual. I was saying that i had never had that happen. I was also guessing that you were saying something about it because running water through the sump would allow the skimmer to pull out more gunk from the corals going sexual....ahh never mind :lol:

I dont want to run the dart on my CL...I want something bigger. I was saying the dart for the return from the sump instead of the barracuda I originally thought. Then I said I might use a hammerhead (I was going to use a 2nd barracuda) on the CL if I run it through the chiller.

I dont mind the noise of the water as long as its not slurping down the drain. Its kinda relaxing to me...I on the other hand cant stand to hear hummmmmmmmmmmmmmmmmmmmmm from the pump 24/7. So I have a chance to stick them outside...so I am

 

[mikester]

AND, deltec has based their whole recirculating skimmer line on the idea of lowering the throughput and passing the water through the skimmer mixing pump multiple times. But thats a whole other can of worms...

I don't think that is the point to a recirculating skimmer. The recirculating aspect is not so that you can pass the water through the skimmer multiple times. It is more efficient to skim effectively in 1 pass with a longer contact time than it is to pass the water through multiple times with a shorter contact time.

The point of a recirculating skimmer is to separate the air injection from the flow through the skimmer. You need a relatively high flow rate through a venturi or beckett to get a sufficient amount of air injected into the skimmer, and to do that you end up passing the water through the skimmer too quickly. By using a recirculating pump to inject the air, you can keep the flow rate slower through the skimmer and increase the contact time.

None of this contradicts what you are saying about low sump turnover rates - in fact with a recirculating skimmer it would work even better with a slower flow, which is exactly why I am thinking of changing my setup.

 

[Herbert T. Kornfeld]

NOLACLS, you said..."I was referring to when you said something about having corals go sexual. I was saying that i had never had that happen. I was also guessing that you were saying something about it because running water through the sump would allow the skimmer to pull out more gunk from the corals going sexual....ahh never mind" LOL, no I was just saying that the low flow idea must work because DNA had his corals going sexual on him...and thats more than most of us can say.

mikester,
I dont see quite where you are coming from, but let me just put it this way...deltecs, and all other recirculating skimmers, operate by running a mixing pump that is many times larger than the throughput that enters at the top, and exits at the bottom. Water is recirculated many times before it eventually exits. By running a sump with a low throughput of say 200gph, and a skimmer with a throughput of 1000gph, you are recirculating the water just like a recirculating skimmer. The only way that this could hurt skimmer performance is if you believe that your skimmer can clean more than half of the contaminants in your water in a single pass.

edit: just read your last line:"None of this contradicts what you are saying about low sump turnover rates - in fact with a recirculating skimmer it would work even better with a slower flow, which is exactly why I am thinking of changing my setup." -so nevermind So you also believe its possible that a low flow pump in the sump could in fact increase the skimmer's abilities?

 

[maldivian_chicken]

I'm with Herbert on this one. I've been running my 100g
with just a eheim 1250, it double duties driving the calcium reactor
as well, I've been planning to use it to drive the phosban reactor as well. BTW, the eheim has been running 24x7 since 1992, and
I bought it used.

Last summer I tried switching to an even lower powered pump
(eheim 1048), but it didn't give enough flow to clear the surface
film on the water.

Powerheads, streams, closeloops, ..etc are much more efficient as circulating water since they don't incur a head loss.

 

[Herbert T. Kornfeld]

chicken,
do you run a skimmer in your sump? If so, what?

 

[Entropy]

I have been thinking about this and have come to the conclusion....

What's the difference other than power usage? If you flow 700 gph through your sump and the skimmer pulls 700gph and is 50% effective (example only) or you go with 350 gph flow and the 700gph skimmer now works 100%, what is the net difference?

Unless you can prove the skimmer actually works better with a smaller amount of tank water available, I don't think you have solved anything (other than as noted, using less power for the return pump).


To throw another wrench in to the equation I just realised that since I added my 110g refuge to the system I am not really skimmer my display tank at all directly. My AquaC sits in my refuge which is fed an unknown amount of flow from my 3/4 drain which eventually flows to the sump, while the 1 inch drain directly feeds the sump. To make matters worse my refuge is full of macro algae which is competing with the skimmer for nutrients. So I guess in a way I am using your lower flow idea without actually lowering the flow.

 

[maldivian_chicken]

I run a ASM g3 in the sump.

 

[NOLACLS]

Herbert :lol: gotcha...I thought you were saying something along the lines like if an anemone dies...you want to have a skimmer or something to pull the mess out. Slowing the flow by the skimme rto me would make it re skim the water more thus pulling the junk out faster. I dont really know tho I am thinking about making a few changes in my setup. Smaller sump return bigger CL pump and chller on CL.

 

[mikester]

So you also believe its possible that a low flow pump in the sump could in fact increase the skimmer's abilities?

Sure, it's common sense if you think about it.

In my case, I am currently flowing about 1500 gph through my overflows, and my skimmer feed is about 150 gph. So at any given time, 90% of that protein-rich surface crud laden water is passing my skimmer by and going back to the tank. If I slow down my sump turnover to 600 gph, then 25% of the water will get processed at any given time.

 

[durango_doug]

wow, what a break through. why do i have a mag18 on my 90gl? i've been bustin my butt for two weeks trying to figure out how to eliminate the massive amount bubbles and noise this thing creates. i'm running a counter current skimmer, so the flow for that is only like 100gph. i'm really temped to use my mag as a closed loop and get a conservative 500 gph ehiem or something for my return. the only drawback to doing this is the tears that will form in my eyes after i pull out the $150 worth of 1.5" plumbing that this thing needed.

 

[Herbert T. Kornfeld]

Entropy,
mikester covered my response in his...kind of. The big diff is that the water that passes by (unskimmed water from the surface) actually becomes harder to get out because it gets blended back into the water, and the skimmer has to work that much harder to get it out again (oxidation has to be repeated). In a way, the surface area of the tank is used to work in your favor and boost the skimmers efficiency. So then an even bigger skimmer, with higher turnover through the tank is needed to compensate because it has to do more of the oxidation on its own. This is purely hypothesis at this point...but it does have merit. I can see your tank is set up for how you have it, and redoing it would take some considerable thought. Hey, Im not trying to revolutionize, just perpetuate a movement. Maybe the next tank....LOL (you know there is always a "next tank" on the horizon with this hobby)

durango_doug,
well, thats why i made this thread. You could rework it (alot easier to accomplish in the planning stage). How about an eheim 1250 ($60, dead silent, reliable, and commonly found...should give you 150-200gph at 4' head). Then make the closed loop with the mag18. Dont cry, if it helps & FWIW, think about the more bang for the buck (not to mention watt) you will get from using your mag as a CL pump. Less heat into the tank too which these pumps are kinda known for. Less noise...less headache...that should dry up those tears pretty fast. Say hello to the EAP world of plumbing with 3/4" PVC. LOL. BTW, how do you spend $150 on 1.5" plumbing anyways? What...do you have 4 check valves or something?

edit: using your mag18 as a CL pump might be too much for a 90g...you had better split those ports off a bunch! Heck, a 1" spraybar along the whole back of the tank might even be pretty strong. Maybe a smaller mag...as the only real advantage I was thinking with the mag18 would be that it does have enough pressure to use eductors with (an 1800gph pump can be as low as 30some watts, but w/o the pressure...so we might as well use the pressure that the pump was designed for to some advantage, right? ie: use the 145watts to its fullest potential)...but that would turn your tank into a typhoon experiment. I would look into alternatives to the mag18 down the road if I were you. I have nothing but nightmares with mags anyways.

 

[dpstrand]

I don't understand why everyone is saying closed loop pumps encounter no head loss and produce no (less) heat. Are people mounting their closed loop pumps up near the surface of the tank?

If the closed loop pump is down under the tank near the sump, it would encounter just as much head pressure as the sump return pump (assuming the same height return and same size piping). It would produce the same amount of heat also. Am I missing something here?

 

[Herbert T. Kornfeld]

A closed loop has equal pressure going in and out...no head. Sure, there is some back pressure from elbows and the like, but the idea is that a closed loop, when shut off, will simply stop...not backflow like a sump return. This allows for the use of more effecient, low wattage, high-flow pumps than with a sump return.