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MAG 5 too much flow for a 20g?


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Im setting up a new 20g long with a 10g sump, so i am in need of a return pump. I will probobly have a SCWD hooked up to the line, and if not, i will tee off the line and have 2 return spouts.


Do you think a MAG 5 woudl be too much flow? it is rated for 500gph.




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Again, I am a STRONG opponent of tsunami'ing tanks. More water flow might not be necessarily better. 500gph in a 20g (25x turnaround/hour) seems awfully high, unless you throttle it with ball valves.


However, it really depends on your aquascaping, water flow direction and inhabitants. If your Xenia or fish get tossed around in the tank, so that you can't even see it gently rocking back and forth anymore, then you have way too much flow.


It needs to look natural - water flow in natural reefs is barely noticable close the bottom and a little stronger and turbulent as you approach the surface. I am a diver and have seen many reefs "first hand". It is not easy to translate this into a closed tank setup, but in the sea on the bottom you usually have drift about 4-5 feet per second and a surge of about 2-3 feet.

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well, i forgot to say this, but it is for a SPS and clam tank. And i migth hook up a scwd, so will take off pressure. I am deffinantly using ball valves!

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Im gonna run a mag 5 on my custom 15g with 3 feet of head and 3 right angles and such. after some test runs im thinking of doing a mag 7.


as long as the fish arnt getting blown into the sides of the tank its all good.

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If u run the mag 500 with the scwd it wont be enough, youll want more down the road...


I have a mag 5 on a closed loop runnin my 6 gallon and its not all that much it breaks out into 4 outlets.. but only 3 of them function.. it is mostly sps frags and they seem to enjoy the turbulent current..

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I actually got a Mag 5 yesterday for my 20L and installed it in my 10g sump. It also goes through a SCWD. I tested it yesterday by runnning it "dry" (only filled up the sump and pumped it into my empty 20L) and I am getting a hell of a flow with the ball valve fully opened. I agree that a Mag 3 is probably right on the low edge of what you should have on a 20g, so I opted for a Mag 5 that I can throttle down.


My verdict is not out yet, but I will probably try to go for about 300gph, as I have a 20L which most likely needs a little bit more horizontal flow, because of the length. I will start the tank tonight/tomorrow and keep you posted.

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I am trying to figure out what I need for my 29 gallon. I have a mag 3 now am not sure if I should use that one the close loop for the scwd or use that for the sump return. Right now I am thinking about getting a mag 7 for the return as its going to have to go up about 4 feet or so.

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fishy610 , be sure to post some pics! Please do keep me updated on your tank. I think it is funny how many people are settign up tanks now.

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