sump turnover vs. skimmer performance

[Lance]

Hmmm.

I've heard this argument many times before: "Does the turnover of water through the sump have any bearing on the performance of the skimmer?

Some people say that less turnover gives the skimmer more reaction time with the tank water and therefore skims better. Others say the more water from the DT available to the skimmer makes for more effective skimming. I have to say I leaned more to the third scenario: that it doesn't make any difference as to skimmer performance. While slower movement through the sump may be beneficial to the flora and fauna living in the sump, it doesn't affect sump performance.

After recently changing return pumps, I may have to change my opinion. My old pump was moving water through the sump at slightly less than twice the rate as the new pump. Skimmate is definitely darker and smellier with the slower water! 3 days, however, does not prove anything so I will monitor the skimmer closely over the next few weeks and see what happens. Thoughts?

[marie]

When I changed to a lower rated pump, I noticed I was getting more skimmate

[Madmak]

I think there is a pretty wide range of flow where the skimmer will work well but too much or too little flow isn't good for anything. I match my return pumps with my skimmer pumps (about 1200 GPH) and use a closed loop (4500 GPH) for DT flow. I then only run 150 GPH through my refugium.

Seems to work well for me.

[sphelps]

I think the slower return rate is related more to effective surface skimming than skimmer contact time. I don't believe for a second the theories relating to matching skimmer flow rates with return rates as they completely independent. However a slower return rate can mean a thinner film being removed from the top water of the display which in theory would hold a more concentrated amount of lighter organics however there are many other variables at play.

Another really important factor to consider is sump design. Skimmer chambers should be designed to trap lighter organics with a baffle and be sized properly for the flow rate of the sump. Ideally organics should float in this chamber just like they would in your display and become trapped with the only exit into the skimmer. I've seen many sumps where water exits the skimmer chamber over a baffle instead of under for example, this setup would probably benefit from the slowest possible flow rate.

At least that's how I look at it.

[Lance]

Originally Posted by sphelps

I don't believe for a second the theories relating to matching skimmer flow rates with return rates as they completely independent. However a slower return rate can mean a thinner film being removed from the top water of the display which in theory would hold a more concentrated amount of lighter organics however there are many other variables at play.

Another really important factor to consider is sump design. Skimmer chambers should be designed to trap lighter organics with a baffle and be sized properly for the flow rate of the sump. Ideally organics should float in this chamber just like they would in your display and become trapped with the only exit into the skimmer. I've seen many sumps where water exits the skimmer chamber over a baffle instead of under for example, this setup would probably benefit from the slowest possible flow rate.

At least that's how I look at it.

I'm with you: I think flow rates are irrelevant. So, whatever I did to make the skimmer more efficient was purely luck IMO. And like I stated above, 3 days could be just coincidental.

[Madmak]

I've seen sphelps' tank and I'm not sure anyone could find fault with his water quality/clarity.

I work my skimmer pretty hard, this is 3 days of an Elos 4000 on a 200G after 2 200 micron socks changed every 2-3 days.