Pump Question

[wrightme43]

John I see what your saying about detirus. That makes sense. In my tank, I have a filter pad in the overflow. then into a filter sock, then thru another filter pad. then into the skimmer then on to the return. I dont really get alot detiruis in my skimmer mainly what I see in it is a black slime. I think and I may be wrong that it is dissolved organic matter that will be equally dispersed through out the tank. I am trying to understand this and really want to learn why people believe what they do. I hope that is comming across. Steve

 

[fishermann]

Heck Steve you don't even need a skimmer LOL. Yeah about all you have left is organics to skim, but alot of people don't run all the other filtering equip. you are and are relying on their skimmer to remove alot of what you are by other means.

 

[DonW]

OK now in my mind I see it different. If that were the case why would you put a fan on your radiator in your car. Why would a heater have a blower motor. How does water boil while I stir it. and how come my make up water gets hot with a power head blowing on the titianium heater? I dont care how fast water is moving if it is in a closed system all of the water is treated the same no mater how fast it is moving. If it were a open system that would make sense. I would think that a fast moving system would maintain equilibruim of temp and cleanliness better than a slow system. Just my opinion. Steve

Allowing the skimmer to get the crud in the first pass is more efficient. You dont want that detrius going back into the tank to rot. You dont drive your car through the car wash at 75mph and expect it to get clean. I guess if you went through enough times it might get clean, as long as it doesnt get any dirt on it as you go around to reenter.

Don

 

[wrightme43]

Oh sorry Don that was in refference to the heater. I think I am just going to shut my mouth on this one. You all have a good night. Steve

 

[dnjan]

Allowing the skimmer to get the crud in the first pass is more efficient. You dont want that detrius going back into the tank to rot. You dont drive your car through the car wash at 75mph and expect it to get clean. I guess if you went through enough times it might get clean, as long as it doesnt get any dirt on it as you go around to reenter.

Don

There is nothing majic about a sump that causes detritus that makes it to the sump, and then gets pumped back up to the tank, to sink whereas detritus that stays in the tank stays in suspension. If there is enough flow in the tank to keep detritus in suspension, it will keep detritus in suspension - whether it comes from fish, live rock, or the return from the sump. If you have a slower rate of flow in the sump, then you will just be removing detritus from the tank more slowly.

There is an advantage in slower flow in the sump, and that is when the slower sump flow allows some of the detritus to come out of suspension (and settle in the sump). Unfortunately, this requires that the sump be periodically cleaned to remove the settled detritus. Most people don't do that. Instead, some people use filter pads or filter socks in the sump to collect some of the detritus. In that case, detritus-removal efficiency is increased by increasing flow to and from the sump.

Also, the statement about a skimmer removinng less material when the sump flow is fast than when the sump flow is slow, is generally not true. Most skimmers aren't smart enough to know how fast the water in the sump was moving before it got sucked into the skimmer pump. A skimmer just skims the water that goes through the skimmer pump. Independent of the fraction of total sump water, as long as the flow through the skimmer is the same.
If, however, by changing the flow rate through the sump you also change the water level in the sump, you could affect skimmer performance.

 

[DonW]

NO. But here's something that may explain better than I can.http://ozreef.org/content/view/104/2/

Don

 

[les]

Don,
The only thing I really picked up on that link was that a person should have the most efficient skimmer possible and the skimmer seems to work better at removing DOC's if the skimmer flow rate is 2-3 time the sump flow rate.
That being said, how would a person know if your flow rate is to high through the sump? Would there be any visible signs in the reef tank? Is there some advice as how to check?
I ask this because on my existing system I flow about 4000GPH through the sump/fuge. I know that this isn't quite in keeping with the trend but as far as I can tell it works. My macro grows well and my skimmer skims well and corals grow and the tank is stable.

Maybe we should start a different thread to continue this discussion.

Les

 

[DonW]

Measure organics. Or just try to match the skimmer flow. I measured organics and found that with my return pump up full bore organics went up. With the bv closed about 30% organics went down. Then I opened it back up and organics went up. This going from about 1Kgph to 700 gph. Low and behold my skimmer pulls in about 700gph.
Now granted this is with the salifert organics test kit. What it actually measures is beyond me. I would love to here what test anyone else has actually done to prove otherwise, rather than stating something is just untrue.

Don

Don

 

[les]

Don,
When you tested for organics and found them climbing or generally higher, did you notice any effect on you tank inhabitants?

 

[DonW]

Don,
When you tested for organics and found them climbing or generally higher, did you notice any effect on you tank inhabitants?

Absolutly none, this isnt to say that there wouldnt be long term effects. The idea is to make the system as efficient as possible so that there isnt a tank crash down the road. In reallity this is the point to me even bring this up. Not to say that you cant have a healthy system with tons of sump flow. Why not make all those bucks your spending go a little further by making the system efficient as possible.
I like the comparison of the double flush. We have all seen a toilet that had to be flushed twice to dispose of the waste. Why not just get a better one or properly adjust it so it only takes once.

Don

 

[dnjan]

Simulation is not necessarily Science

Simulation is useful to interpolate between measurements (to eliminate the number of experiments that must be run), but is generally dangerous to use for extrapolation or to develop conclusions when there is no measured data to support the conclusions. Simulations are subject to the limitations of the model(s). Simulations are useful in identifying combinations of parameters that should be investigated experimentally, but cannot be used to develop conclusions without experimental results to support the conclusions.

In the case of the simulation you referenced, the author(s) clearly state (with respect to flow rate through sump affecting DOC concentration):

Why this is the case yet is not known yet, have to look into it more, as it contradicts the result when the skimmer rate is increased.

This means that the authors aren't ready to conclude that a slower flow rate through the sump is better, and others looking at the results surely shouldn't make that conclusion either. It does, however, point to either a shortcoming in the model or a previously un-recognized characteristic of DOM removal.

In your case (where you measure a change in tank organic content based on sump flow rate), there are many factors that can affect the DOC content measured in the tank. Did water levels in the sump change? Was the added turbulence in the sump (due to higher flow rate) causing detritus that had settled in the sump to be re-suspended (and then re-introduced into the tank)? Is it reasonable to use results from a qualitiative organics test like the sailifert one to make quantitative conclusions?

 

[les]

I like the comparison of the double flush. We have all seen a toilet that had to be flushed twice to dispose of the waste. Why not just get a better one or properly adjust it so it only takes once.

Don, :lol: :lol: :lol: :lol:
I gotta say that comparing a tank let alone mine to a toilet that needs to be flushed more than once is a hoot. (Some of us are regular muli flushers)
I am glad to hear that you noticed no effect on your tank critters based on DOC loading of the water column. On my new setup that's in progress I may reduce the sump flow to about half of the skimmer through put. It seems to me that that would be a good idea when building a new system.

Let me know what you think.

Les

 

[fishermann]

I agree with you Don, why would you want to put that detritus back into your tank, I don't care how much flow there is in the tank, once it makes it to the sump where the skimmer is,giver the skimmer time to skim a higher volumne of water before being dumped back into the tank, I sure wouldn't drive my car through a car wash at 75 mph and expect it to be cleanthe first time or even the second. This is a viable comparison to what is happening in the sump/skimmer situation.

 

[wrightme43]

This is very interesting to me. I am still not convinced one way or the other. I am going to start a thread on sump flow rate. I hope you all come and put your opinions in. I may have my concepts mixed up or just may plain be wrong. I believe this is something that needs its own thread. Steve

 

[Jiddy]

Good Steve, start a whole thread on Sumps, im not very knowledgeable in that area yet. But from a practical standpoint the speed of water wont make the skimmer work any faster or slower, it just moves the water in and out while the skimmer cleans water (fast or slow)

 

[wrightme43]

Done deal. It is called the great sump flow rate debate. If you search for it you should find it. LOL Steve