How to Measure and Improve Circulation in Tank

[Patrick Cox]

I have a 48" tank that is 24" front to back and 20" tall. (about 100G). I am running 2 MP40s, one on each end, and I would like to assess the circulation in my tank and then decide if I should add another pump or two and then where I should place them?

My objectives here are...

1. Keep as much debris suspended in the water column as I can so it will move out to my overflow and sump.

2. Maintain adequate circulation to keep my SPS healthy.

Here is a current picture of my tank.

So any thoughts on how I can determine if my circulation is adequate in the tank, where I might have dead spots...etc. and then where I may want to consider placing another PH will be appreciated.

Thanks!

 

[lionfish300]

IMO I think you should be ok with what you have for right now. Down the road when you have more corals or big colonies than I would consider add more flow

 

[Mr.Fishtank]

+1

Two mp40s will work well with your low aquascape. I would set them on reefcrest mode at 60%. Anti-sync if you have the reeflink.

 

[DesertReefT4r]

Personally I would mount them on the back glass. Sync them together, run on reef crest mode at 50-70%. Start low with the flow and see what it does to the sand and how your corals react. Mounting them on the back glass will give you better circulation due the the tank being shorter front to back than side to side, the flow will reflect off the front glass, down to the bottom, across the rocks then back up the rear glass. Making a good waste suspending circular gyre type flow.

 

[Subsea]

My tank has the same footprint but is deeper at 24”. I like your aquascaping with respect to large open spaces to promote good circulation. You might consider getting a little taller with your two island landscapes and eliminate the bridge in between. Is that a clam in the middle?

On every 48” long tank that I own (six indoor and ten outside). I use a vertical look current. Using pump to move water down the length of the tank at the surface with a down flow on the opposite wall and water returning on the bottom side. This circulation is a closed loop which means that once the current is established the inertia of mass helps maintain the current velocity. In my 120G tank one MaxiJet 1200 circulates water across the surface with a second pump jetting water down on the opposite wall. Initially, I had a third MaxiJet for circulation, but the current velocity was too much for Green Sinularia full polyp extension.

With your present arrangement, you should achieve random chaotic flow which is best for most corals. As random chaotic flow approaches turbulent flow, you can easily prevent polyp extension and even damage coral.

 

[Patrick Cox]

My tank has the same footprint but is deeper at 24". I like your aquascaping with respect to large open spaces to promote good circulation. You might consider getting a little taller with your two island landscapes and eliminate the bridge in between. Is that a clam in the middle?

On every 48" long tank that I own (six indoor and ten outside). I use a vertical look current. Using pump to move water down the length of the tank at the surface with a down flow on the opposite wall and water returning on the bottom side. This circulation is a closed loop which means that once the current is established the inertia of mass helps maintain the current velocity. In my 120G tank one MaxiJet 1200 circulates water across the surface with a second pump jetting water down on the opposite wall. Initially, I had a third MaxiJet for circulation, but the current velocity was too much for Green Sinularia full polyp extension.

With your present arrangement, you should achieve random chaotic flow which is best for most corals. As random chaotic flow approaches turbulent flow, you can easily prevent polyp extension and even damage coral.

Hi,
Thanks for your reply. I actually just added some more rock to my tank. I am not quite finished but below is where I am currently. With the new rock I got some additional snails and some small urchins. They are doing a great job of cleaning my rock. And at the moment I do have good polyp extension.

I lowered my two MP40s about 1" and I have been running them at 60% in Reef Crest Anti Sync. I am still considering a powerhead behind my rock work but I haven't made up my mind on that.

Oh, and yes, that is a clam. You can see it better now with my new scape.

Thanks!

 

[Subsea]

Nice.

To measure velocity in a tank, you should feed flake food and observe. With my vertical loop current it is easy to time a flake particle through 1’ of tank travel. I don’t chase numbers. I watch polyps. I see where detritus accumulates. I adjust flow nozzles or vacume accordingly. For me, bioindicators work best. Withdrawn polyps is one bioindicator with several possible differrent unrelated reasons. Cynobacteria mat is a bioindicator of phosphate. Because cynobacteria can absorb inert nitrogen gas and convert to nitrate, it only needs phosphate to flourish in a 30:1 ratio of nitrogen/phosphorus. A Randy Holmes Farley article on phosphate describes how cynobacteria convert inorganic calcium/phosphate into organic phosphate using a biofeedback loop to complete process. Imagine that; Smart bacteria.

 

[fishguy597]

I just add amino's once and a while. The yellow coloration will show where your flow is along with dead spots.