Sump passthrough (What is the most beneficial, more or less?)

[OranguTang]

Another reefer (feel free to join in if you are watching :)) and I were discussing our views on the flow through our sumps and other filtration earlier today and it sparked some interest in me. I think it is common knowledge here that many of us are lead to believe that 3x-5x through the sump is the best rate at which we should be using.

However, he proceeded to discuss how he does not do that, nor did it sound like he ever would...it did just not make much sense to him. It seems he is moving closer to 20x through his setup, with no ill effects. If anything has seen GOOD results.

So why is it that many of you/us recommend the former to fellow reefers? What are the benefits to slower flow through the sump?

Also how do you run yours? And how do you feel about high flow through the sump?

[Randy Holmes-Farley]

There is no benefit to having water move more slowly through a sump, and there may be some benefit if processes taking place on it are becoming limited by the flow (say, pH rise in the sump when adding limewater, or skimming being limited by reduced organics in the water).

The rule of thumb about turnover has more to do with recommended flow rates in the tank, not really flow through the sump.

[OranguTang]

I favor high turnovers in the tank, but I have always been told, and have told people with no objections that you should shoot for 3-5x, even melev recommends this? Why do you think?

I have about 80x in the display but only about 3-4x through the sump. I could be doing a lot more though...

What do you do on your tanks personally?

[jlunde]

I just got a 180 gallon and I'm trying to determine what I should get for my return pump. I was thinking Eheim 1260 or 1262. I'm going to jump on this thread to see what kind of responses people have to this topic. Do you need to decrease the flow through your sump if you have a fuge? That then gets into the design of having, for example, 75% of your water going into your skimmer section and the other 25% going to the fuge...which of course reduces the gph going to the fuge...making the flow slower.

[ConsultantERP]

You would think that if you were trying to get waste to settle in the sump, then a low flow rate would give it a chance to settle. A fast flow rate would simply mix it up with the water and push it back to the main tank. Kind of like a settleing pond in a waste water treatment plant.

80X in the tank would easily keep you rocks clean.

How would your water ever be clear if the waste did not have somewhere to settle so you could remove it. Maybe a filter sock.

Not to mention your drain pipes would have to be huge to handle 20X turnover in a 100 gallon tank. 2000 gallons per hour

[jlunde]

ConsultantERP - I'm guessing the high amounts of 20x or 80x flow rates include the use of pumps in the tank to produce more water movement. OranguTang stated he only has 3x - 4x in the sump.

[OranguTang]

You are correct about the 80x ( turnover in my display ). The reference to 20x was to the high turnover in the sump we were talking about above and I personally have 3x-4x in my sump.

Anybody else? Experiences?

[tim.hunt7]

im running about 14x after accounting for head, with out accounting for head about 2100g/hr 20x in my 100g tank with 50mm plumbing i still have silt building up in dead spots at the bottle of some of the baffles and i have a small fuge

[tim.hunt7]

and about 35x in my main tank

[Nereaga]

I have 6x going through the sump and about 25x in display....

[Agu]

The only sump I currently have has somewhere well under 10X turnover in the sump. That seems to work for me.

As a practical aspect where's the advantage of circulating vast quantities of water through a sump ? You're paying for a powerful pump and the electricity to run it just to create high flow in a sump ? Doesn't make any sense to me. Running a smaller pump and having additional flow in the tank where you need it makes more practical and financial sense.

That high flow can create additional problems. There are thousands of posts on RC about problems that can be directly related to flow through a sump. Everything from loud overflows, splashing noise in the sump, salt creep, and microbubbles returning to the tank. How many times has the solution been to put a valve on the pump to reduce flow?

[Randy Holmes-Farley]

I have about 80x in the display but only about 3-4x through the sump. I could be doing a lot more though...

As mentioned above, such a comparison is confusing turnover and flow. What exactly "turnover" means in a sump that might have many water removal and return sites is not clear to me (skimmer, ozonizers, refugia, chillers, UV sterilizers, main tank return, various filters, etc.).

But that aside, there are many different processes that take place in different folks sumps. Some benefit from higher flow and turnover than others. Adding high pH supplements, for example, is less problematic with high flow and especially high turnover in the sump.

Nearly all of the processes in the sump can be reduced in efficiency by too low of turnover, and the turnover through each piece of equipment should be optimized for each process.

For these reasons, I do not think a simple rule of thumb is especially useful unless you are considering what you are doing in your specific sump, whether all of the turnover travels through a refugium or not, whether it all goes through a skimmer or not, etc.

[Misled]

<a href=showthread.php?s=&postid=12203490#post12203490 target=_blank>Originally posted</a> by Randy Holmes-Farley
whether it all goes through a skimmer or not, etc.


This is the setup I'm working on now. The "flow" in the tank will be about 60 times. The flow through the sump will be about 3 and a half. This is what the skimmer is rated for for flow through. All water going through the sump/fuge will pass through the skimmer first, then the fuge, and then returned to the tank.

[Randy Holmes-Farley]

That seems like a fine plan to me. :)

[OranguTang]

<a href=showthread.php?s=&postid=12203490#post12203490 target=_blank>Originally posted</a> by Randy Holmes-Farley
I have about 80x in the display but only about 3-4x through the sump. I could be doing a lot more though...

As mentioned above, such a comparison is confusing turnover and flow.

I know you understand what I am saying, but for others...

I have 80 times my display tanks volume in GPH for FLOW in the display. I have 3-4 times my displays volume in GPH going through my sump.

[macreefster]

i have a 70 gal display with 4900gph flow within it. i have an eheim 1262 return pump in my sump that sends about 25% of its flow to a mud refugium that circulates back into the sump and the other 75% going back to the display tank. a eheim 1250 feeds my skimmer that feeds back into the sump. my sps corals and gorgonians seems to love the flow in the display tank and i will increase the flow in it with a vortech or tunze with controller, but i want to upgrade my 250w HQI's with lumenarc reflectors first. why couldnt i have found this site before i purchased my equipment?..lol. better late than never i guess.