Powerhead in a 20 gallon long? yes or no?
 

Hi
I just did a 20 gallon long Nano reef, and finding out that this powerhead (Marineland maxi jet 1200) really moves a lot of water, too much more this tank, I have 2 new Hydor Koralia Nano Evolution 240 GPH coming in Friday, I hope, Do I really need to runs this powerhead, or can I get away with just using a Aquaclear 70 filter and a Rio Nano skinner, for a few days, until I get a less powerful powerhead.

Thanks

Can't you get the koralia nano and then once you get them you return the maxijet?

As for the current, it really depend what's in the tank. I don't think it would be critical to be with a low flow for a few days, as long as you have the skimmer running so there is no lack of oxygen.

I have some SPS that are in very low flow and they are growing well and thriving.

The problem I see with less current is that heating might be not too uniform and there might be some part of the tank warmer than other.

20 gal long
 

a spray bar might be better for the tank

You can lower the powerhead down to the middle of the tank then pointing its nozzle about a few inches into the front glass instead of letting it flow straight across the tank. It will reduce the amount of flow from its direct strong nozzle.