400 gallon project

[Red_Six]

Nice tank.

I have the package as well. I had one red sponge that dissolved away in about 4 months. After doing some research I came across this article by Randy Holmes.

http://www.advancedaquarist.com/issu...03/feature.htm

In it he says, "Sponges are the second largest consumer of dissolved silica in the ocean." I would be interested in seeing if the addition of silica to your tank lets them survive.