Is there such a thing as too much water movement?

I have a 30 gallon reef tank with a Rena XP1 filter and I also have a Maxi 900 powerhead. I'm wondering if there is such a thing as having TOO much current in a tank? I put the 900 somewhat perpendicular to the output of the Rena (jet nozzle installed). The water isn't boiling, but the combination does stir up the sand a bit.

What's the rule of thumb for how much current to have in a tank? Is the Rena sufficient by itself? Is there a benefit to having the 900 in there as well, or is it more bothersome?

Does increased current pose a problem for polyps, feather dusters, fish, etc?

thanks,
bruce

mogurnda said:

Constant blasting isn't good for anyone, and it's too much if your fish cower in the rocks for protection. On the other hand, animals on the reef often get very strong, surgy movement. Some species of corals, like gorgonians, thrive on a lot of movement, while it will kill some large-polyped species.

You should expect some movement of the sand bed, but not areas blasted clean. With about 200 gph from each pump, I'd say you have decent water movement, especially with the powerhead aimed at the filstar output.

Click to expand...

Gack. Clearly my questions isn't going have a straight-forward answer, is it? Oh well, I guess I will have to try out some options.

I have tried aiming the Maxi 900 at the wall and that helped to soften it, but it was the cause of the sand banks being formed. No areas were being blasted clean, but the surface layer of sand (the live sand, to be precise) was forming a bit of a reef as a result of the Maxi 900.

I have turned off the Maxi 900 and it seems to be a bit more stable in the tank. The Rena generates a fair amount of current as it is, so hopefully that will be sufficient.

Thanks for the comments/ideas guys -- I'll keep an eye on things and try out some alternatives.

thanks,
bruce