120 gallon tank owners (or anyone) - Flow question

[cmtbears21]

Hey there,

As I mentioned, I am about to set up my 120 gallon tank (4'x2'x2') and I was looking for opinions on the flow in the tank from fellow 120 gallon tank owners (or anyone).

I currently have 2 Koralia Controllable 8's (1100 gph to 3500 gph each) and dual return flow from an Eheim 1262 pump in the sump. The 8's would be put on the sides facing each other and run on a wave maker (probably shifting from one to the other every 15 seconds or so).

Will those two plus the 8's be enough or do you think I will need another powerhead or two? If so, where would you put them?

Thanks!
-Matt

[Enceladus]

I would say that it depends on what you're planning on putting in your tank, and the aquascape you had in mind more than anything.

The flow you need will depend largely on what type(s) of corals you want to keep. An SPS dominated tank will demand all the flow you can throw at it, but a tank full of LPS and softies could generally love lower, albeit carefully directed, variable flow rates. It does vary a great deal between different corals in each category too, but that's all part of the planning.

Rock placement is important for this as well. If you want a tank full of rocks with plenty of spaces to place corals, then you'll benefit by having more flow to work around with those rocks. Alternatively, if you have a minimalist design and plenty of arches and open spaces, then with careful powerhead placement you can have rapid water movement through the rocks with only a handful of pumps.

A third consideration would be the fish you want to keep. Most tangs will love a quick and dynamic water flow in your tank, but there are plenty of others that might not handle stronger flow too well. Then there are the ones that might surprise you; an N. Magnifica firefish might be inclined to hide more in the face of strong flow, but could benefit greatly with more food being brought right up to the bolt hole it has chosen to hide out in because of that same flow.

As an example, I run a 125g tang mixed with LPS, softies and a few zoa's and mushrooms. The tank gets its flow from just 2 MP10s (one on constant speed, the other on lagoon mode, both at 100%), 2 Koralia 2's and the return flow from an Eden 155 pump. I do have a fairly minimalist design, with plenty of open water, and everything in my tank is thriving. I'm not particularly interested with SPS corals, and have built the tank around what I wanted to keep.

I guess that's the key to it really - think carefully about the tank and livestock you want the most, and then buy the equipment that works for that.

Hope this helps.

[cmtbears21]

Wow, thanks for the help...that gives me a lot to ponder! I happen to like the look of minimal rock with plenty of open water as well.

I guess really I should run with what I have for now and as I add fish or coral adjust as needed.

Thanks again!
-Matt