How much flow do I really need?

[EDJFA]

When I started my tank a few months ago the LFS guys said I should use 2 Maxijet 1200's. I went with it, setting one up on either side of my tank, a standard 55g, and just let it go. One of them has started buzzing, probably vibrating loudly would be more accurate, sporadically. Which makes me think, do I really need two of them? One of them gives me a turnover of about 22X. I've read everything from 10-45X is ideal.

With both of them running I constantly have sand flying all over the tank. It's not a bunch, just enough for the water to look a tiny bit cloudy. It's a FOWLR tank right now, just some snails, emerald crab, and a couple clownfish. Would I be OK pulling one of the 1200's out? Or should I turn them both back into one of the lower flow options and keep them both in for the cross currents in the tank?

[papagimp]

I havn't used the Pro series maxijets so not overly familiar. two of the running full blast though would be plenty of flow and just a matter of adjusting placement according to aquascaping and all that. You "could" pull one out, but it'll end up giving a very linear flow throughout the tank. I prefer a minimum of two powerheads, maybe just tune one of them down to the lower setting and see what you can work with their? That put you around 30x turnover which is decent. (keep in mind that various corals have various flow requirements, so 30 could be too much for some, not enough for others) For a FOWLR tank though, best to let a fowlr person chime in with their thoughts

[dnguyen1]

I'd definitely stick w/ 2 as a minimum... take out the maxijet that's vibrating and open it up, is there something wrong w/ the impeller? Otherwise replace it.

There's a lot of scenarios depending on the reef you have. you planning on SPS? or anyhthing like that?

[EDJFA]

Not planning on SPS. If I go that direction, I'll start a new tank.

With this one I might add some soft corals, zoos, rics, stuff like that.

[freetareef]

you might be able to get away with one if it is an lps tank.....i would use two.

[unfamous]

Timely topic. I am trying to wrap my head around this whole concept. I have a 90 gallon tank. The return pump is rated 714 gph (Sicce 3.0), i have 2 750 gph powerheads (Koralia 750's) in the tank. This is a total of 2214 gph being moved around in my tank. that's a turn over of roughly 24.5 yet I see people here running 2, 3, and 4 1200 gph power heads in the same size tank I have. I know I'm new here, but isn't this enough?

[thor109]

I have a 75 g I run a mag 3 in sump (300 gph at 4 feet) and two 160 gph power heads. Everything in my tank sways from the flow. My BTA, zoas and xenia are all growing. I switched my maxi pro to 750 gph mode and it was crazy. My fish were unhappy and all the corals kept closed most of the time. Probably from sand blowing around. I think it is some macho thing that bigger/more is always better. I keep hearing that its good to buy a mag 9.5 and than throttle it back with a valve. To me that's Like driving your car around with your emergency brake half on. Why pay to run something you are not using.

[A_Z]

can I use a mag 5 for my return on a 75g ?

[Ron Reefman]

Originally Posted by unfamous

Timely topic. I am trying to wrap my head around this whole concept. I have a 90 gallon tank. The return pump is rated 714 gph (Sicce 3.0), i have 2 750 gph powerheads (Koralia 750's) in the tank. This is a total of 2214 gph being moved around in my tank. that's a turn over of roughly 24.5 yet I see people here running 2, 3, and 4 1200 gph power heads in the same size tank I have. I know I'm new here, but isn't this enough?

It could very well be enough. It depends some on what you are keeping in the tank (zoos, lps, sps?). How you have your rock set up (island, piled up the back wall?). How the powerheads are placed in the tank. Lots to consider. But you are in the right ballpark.

Also, remember, your return pump will have head loss from the pump to the tank outlet and elbows in the return line. So you may not have nearly the 714gph you qouted (unless you already calculated that out).

[unfamous]

Not real sure what the head loss is on mine. The pump is rated at 714 gph but the calculator on the home page doesn't list Sicce pumps AFAIK. Still, with 1 inch line, no valves, 1 elbow, 2.5 feet horizontal, 3 feet vertical, 2 connections It should at worst spec out to 600 gph roughly. still around 23x turnover. My rock is back walled mostly but very open. Lots of "caves" and larger openings. Its also a FOWLR tank. Well, it will be once the cycle finishes.

[T Smith]

I like to have around 10x "turnover" through the sump but I think the key here is not a magic total flow rate number but to have good flow throughout the tank so as not have any dead zones for nasties to pile up.

[EDJFA]

Over the weekend I got a couple new fish, a yellow watchman goby and a foxface. I still had both of the maxijets running in the 1300gph circulation mode in my little 55g. When I looked up at one point and saw the goby stuck in a vortex from one of the maxi's (I'd swear I heard him saying "There's no place like home...there's no place like home...) I turned everything off and then made a decision that it was time to change something.

I tried running just one of the MJs at a time, but it was still a ton of water moving. The goby still couldn't seem to find a place that was comfortable. Yesterday I converted both MJs to the powerhead mode. It puts out about 300gph that way, but I can run two of them. The goby has found a couple of places where he can perch or swim and not get blown across the tank by the flow. And I don't have to worry about him getting sucked into the propeller and getting turned into fish food.

The foxface seems to be much happier too. He hid out in the corner looking all mottled brown for the first day or so. 15 minutes after I made the change he's bright yellow and swimming all over the tank looking for food.

To top it off, the free pulsing xenia frag that I got from the LFS (spend $20, wear your Cardinals stuff, get a free frag) now has a place where it isn't getting beaten up in the current and I'm hoping it will actually start to pump like it was in the store.