Return line plumbing question...

[johnr2604]

ibleedblue65;522380 wrote: I understand the dwell time for the heater but why for the skimmer?

To put it somewhat simple its basically like the heater. It gives the skimmer a chance to get the water in the sump chamber cleaner before returning back to the display.

 

[grouper therapy]

I don't see any need to push tremendous amounts of water through a sump just to obtain flow in the tank. But I don't see how slow flow through the sump makes any skimmer or reactors more efficient. The water from the tank is constantly mixing with the sump water regardless of the water in the skimmer at ant given time. The amount of water entering the skimmer does not change regardless of return pump's output unless maybe you feed your skimmer with an overflow.

 

[grouper therapy]

I guess if it does get it cleaner then it would be offset by the tank water being dirtier since it did not leave the tank as quick. Right? I am asking by the way.

 

[johnr2604]

grouper therapy;522403 wrote: I don't see any need to push tremendous amounts of water through a sump just to obtain flow in the tank. But I don't see how slow flow through the sump makes any skimmer or reactors more efficient. The water from the tank is constantly mixing with the sump water regardless of the water in the skimmer at ant given time. The amount of water entering the skimmer does not change regardless of return pump's output unless maybe you feed your skimmer with an overflow.

Well depending on the flow some of the previously skimmed water might be reskimmed along with new water. The slower the flow the more it does. I'm sure there would be point of of diminished return though. Of course all this is theory and there seems to be no empirical Data LOL.

 

[maestro]

this discussion brings me back to one of the main questions I had during my build... i'd LOVE to be able to back my pump down and make my tank more quiet... Since my powerheads take care of the flow, how do I know how much dwell time is enough?

 

[johnr2604]

There seems to be a lot of debate about it. Some say 3-5x tank volume. some say 5-10. Some say 1 1/2x skimmer feed pump. I normally shoot for around 5x which normally puts me the closest to all those . I don't remember exactly but I believe you Have a Tunze pump that puts you pretty close to that also. Just remember the more flow you do through your fuge the less flow to the tank. Your fuge is what benefits the most from the dwell time so make sure you have the flow turned down pretty far on it.

 

[grouper therapy]

johnr2604;522408 wrote: Well depending on the flow some of the previously skimmed water might be reskimmed along with new water. The slower the flow the more it does. I'm sure there would be point of of diminished return though. Of course all this is theory and there seems to be no empirical Data LOL.

for sure:thumbs:
I guess my next question would be if we left the sump and everything as is and moved the skimmer to the main tank how much more efficient would it be? My guess is that my water quality would be no different especially if I shut the return pump off and tested the water from both tanks I bet it would be the same. My idea of flow through the sump is that it does not have to be any more than you feed the skimmer . It can be more but why?

 

[grouper therapy]

johnr2604;522427 wrote: There seems to be a lot of debate about it. Some say 3-5x tank volume. some say 5-10. Some say 1 1/2x skimmer feed pump. I normally shoot for around 5x which normally puts me the closest to all those . I don't remember exactly but I believe you Have a Tunze pump that puts you pretty close to that also. Just remember the more flow you do through your fuge the less flow to the tank. Y<u>our fuge is what benefits the most from the dwell time so make sure you have the flow turned down pretty far on it.

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Why is that ? how long does it take the algae to absorb the nutrients?

 

[grouper therapy]

By the way John I am not picking on you just trying to understand where and how we came up with this!!

 

[johnr2604]

grouper therapy;522444 wrote: [/U][/I][/B]
Why is that ? how long does it take the algae to absorb the nutrients?

I don't know how long exactly. I Do know most aquatic plants do not like high flow areas. Goes back to the skimmer concept though. If the water is left in longer it returns to the tank cleaner

 

[grouper therapy]

johnr2604;522452 wrote: I don't know how long exactly. I Do know most aquatic plants do not like high flow areas. Goes back to the skimmer concept though. If the water is left in longer it returns to the tank cleaner

Left in what?

 

[johnr2604]

grouper therapy;522454 wrote: Left in what?

The fuge.

 

[grouper therapy]

If you have a 150 gallon display and a return pump pushing say 900 gph and it is flowing into a 100 gallon sump with a 30 gallon skimmer section. That is 30 times turnover in that section. Now if we cut that back to 600gph return pump that equates to 20 times turnover! I don't see where the water could get any cleaner at either of those flow rates. And if it did get cleaner at the 600gph then the water coming from the tank would be dirtier since it had more dwell time in the fish poop.

 

[grouper therapy]

johnr2604;522452 wrote: I don't know how long exactly. I Do know most aquatic plants do not like high flow areas. Goes back to the skimmer concept though. If the water is left in longer it returns to the tank cleaner

True I see the plant (algae concept )

 

[grouper therapy]

Let me explain it this way, If we were to do away with the sump and placed the refugium in a protected area of the main tank (so the algae would not blow around) and put the skimmer in the main tank as well do you think the water would be any cleaner?

 

[grouper therapy]

I should add that the water volume and circulation remained the same in the main tank.

 

[johnr2604]

grouper therapy;522457 wrote: If you have a 150 gallon display and a return pump pushing say 900 gph and it is flowing into a 100 gallon sump with a 30 gallon skimmer section. That is 30 times turnover in that section. Now if we cut that back to 600gph return pump that equates to 20 times turnover! I don't see where the water could get any cleaner at either of those flow rates. And if it did get cleaner at the 600gph then the water coming from the tank would be dirtier since it had more dwell time in the fish poop.

I can understand the reasoning behind that theory. Problem is there isn't a lot of study out there regarding it. Its definitely a healthy topic to discuss. I can only qoute through my experience and research though.

 

[grouper therapy]

I've been told the same thing John since I have been in the hobby and I see no reason to push a large amount of water through the sump. That being said I could not understand how my water quality would suffer since or anything would be more efficient since it is all one system whether it is 5'-15" below or in the same tank.

 

[johnr2604]

grouper therapy;522459 wrote: Let me explain it this way, If we were to do away with the sump and placed the refugium in a protected area of the main tank (so the algae would not blow around) and put the skimmer in the main tank as well do you think the water would be any cleaner?

I think it would depend on how fast you exchanged the water in direct contact with the algea or around the skimmer pump . So it goes back to flow and dwell time .

 

[grouper therapy]

I started thinking about it when I was drawing the plans for my big tank in the basement and was locating the sump. I could not come up with a reason not to overbuild the tank with a blinder wall if you will and just set the skimmer and all in there. i thought why build two tanks.