How much flow in a softi-dominated tank?

[mrwilson]

I have a 115 gallon display tank that has been set up in my home for about two months (the person I bought the system from had it set up for many years with most of the current inhabitants, plus seahorses). In the way of corals, there are a good number of zoanthids, green star polyps, mushrooms, pulsing xenia, and a large singularia (plus a BTA, a few fish, and the usual cleanup crew). For the foreseeable future, I intend to keep softies like these, plus a few LPS.

The only flow in the tank is from a small powerhead attached to a locline to stir the water around along the back wall of the tank, plus the return line from the basement sump (not sure how big of a pump that is or how many gallons per hour it displaces). With these two pumps only, the water's surface is barely agitated at all, and there is only a small apparent current in the tank. (Little flow like this presumably made good sense when this was a seahorse tank.)

So knowing that more flow would probably be a good idea, I bought an Ecotech Marine Vortech, which moves 500-3000 gallons per hour. It works great, in the sense that it is very quiet, was easy to install, and takes up very little room inside the tank. However, even on the lowest setting, at 500 gph, it appears to me to be really blowing things around. The xenia and the anemone's tentacles, in particular, look like they are being whipped around quite a bit (although I suppose if the BTA doesn't like it, it will probably move) The singularia, however, does have a nice swaying motion to it now.

That's a long-winded way of asking: is this a problem, or am I just not used to what a tank with adequate flow is supposed to look like?

[mg426]

Around ten times tank volume/hr should work for softies.

[steven_dean17]

Different corals need different flow. Slow, medium, fast. Look them up and see what each requires and move them if you have to, but moving the flow would be better. That tank you have is very deep correct? The pump you are using although a very good pump blows in one direction. I would point that pump at an angle that would allow the water to move in a circular motion, since you can't point it up or down. That being said, I don't know if you will be able to make that water move well at the surface without another pump closer to the surface of the tank. I'm not telling you to buy another 300.00 pump, a much cheaper one would do very well as a second.

[Avi]

Well, IMO, the best answer is...the most that you can have without blasting the coral that don't like being blasted can take. I think your best yardstick would be the xenia, particularly if it's of the "pumping" variety. If the flow's inhibiting the pumping, then it's too strong for that xenia...Maybe you can move it to a place that a bit protected. Overall, even in a tank without SPS, I find that the more flow the better so long as nothing is adversely effected by the amount of movement. Even where there is primarily soft coral, I think that a good deal of movement is best. Not only does it keep the coral clean by constantly removing detritus that can foster an unsightly and even deadly micro-algae growth on it, but flow often tends to generate growth. Also, it keeps the rockwork cleaner and any detritus in the water column where it can be drawn to your skimmer for sanitation. So, if you need to, move the coral that aren't so well-suited for more flow and crank that Ecotech up (I just got one and I think it's great.)

[mrwilson]

Thanks so much for the responses so far.

This tank is a flat-back hex design, about 52" wide at its widest point, about 22-24" high, and 22-24" deep (I can't remember exactly). Besides the hex part, it is pretty much the same size as a standard four foot wide 120 gallon, so it isn't particularly deep.

Vortechs cannot be pointed in any direction. They are designed to create a low-velocity, wide current. You can, however, move them easily to different spots on the sides or back of the tank. I've tried everywhere, but because such a wide flow is created, there are really no dead spots where I can shelter the pumping xenia. I've moved some of it to a slightly more protected spot sort of in a cave (but still open to light), so I guess we'll see how the more protected xenia does as compared to the xenia that is exposed to the more direct flow.

How much flow is good for an anemone? The answer seems to generally be "moderate," but how much flow is that?

Another question related to flow: should I just leave this on all the time, or put it on some kind of a timer (so that it's off at night, for instance)? The ocean's currents are of course "on" all the time, so I presume the same should be true in a reef tank?

[Avi]

Leave the water movement on all the time...The only time I ever turn it off is for feeding the coral and so I want to give some slower eating coral time to ingest the food.

[DrBegalke]

to me, moderate is roughly 20x volume.

a lot depends on pump placement though.

[criticle]

mabey two maxi jets at each end of the aquarium should work