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Water Circulation

3513 Views 3 Replies 4 Participants Last post by  Doug1
Just a quick there such a thing as too much water circulation??

I recently set up a 75 gal reef tank. I'm running a SEN 700G as the return pump. It seems to REALLY circulate the water in the tank. I was also going to put a powerhead or two in the tank but I'm not sure that I need to. I don't want to make the water too "rough" for the fish.

Also, one more tank is a 75g AG reef-ready tank. Does anyone know the flow rate of the overflow on that tank?? I couldn't find it on their web site. Thanks in advance for your help. I've had a saltwater tank for a few years but I'm just getting started with my first real reef tank so I'm sure I'll be back with lots of questions.
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In my opinion, yes, there is such a thing as to much flow. It depends on what you are gonna have in the tank. If you are going for a primarily stoney reef, then you have a little more flexibility. If you are wanting softies, or soft tissued stoneys (frogspawn, bubble coral, etc) then you don't want tons of flow, it can damage them, or prevent them from opening. Plus, those poor fish that have to swim "up current" to get from one side to the other. ;) Just my humble opinion. :)
I think in most cases corals, depending on the type benefit from water movement. In the case of soft corals and the large polyp stoies(hammers, frogspawn, bubbles,etc) steady currents, with some alternating or eedy swhirls work well. Where as the SPS type, typical reef builders are found in areas of often times violent water velocities. Alternating devices such as the Sea Swirl or SCWD(squid) are favored to break up the constant linear(straight on) water flow patterns
This is also the theory behind wavemaking devices that alternate powerheads, so that its not always the same direction of movement. You might try wider fittings where the return water enters the tank, it should provide volume but a wider gentler current than for instance the smaller line-lok pointable nozzles. Ideally the same pump pushing same x amount of gallons per hr will have to accelerate the outflow to move the same amount or water. Simplified version as there are always friction and head losses to factor in but think in terms of a water hose open full bore, no attachments, it produces a stream of water that starts same size as the opening and spreads some but only squirts out so far.
Add one of those pointy nozzles that produce a thin concetrated stream like you would use to hose of the driveway, the water goes farther with the force concentrated in a smaller impact area so its able to push more debris , than if you used just the unimped ed hose . Remember what happens when you put your finger on the end and cause the thinner stream
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