In the ongoing saga of learning how to run a propagation tank I thought I'd share things as I make mistakes so others can learn from my screw-ups. I originally set up the Nem baskets but wasn't completely happy with them so I thought I'd go a different route and still be able to run a frag section in the tank. I removed the baskets and placed the Nems directly onto the bare-bottom of the tank. The thought was it would be easier to clean and give the Nems more of an opportunity to find their preferred light level instead if being in an 8" shallow box. This seemed especially important with any wild Nems kept as they simply don't acclimate as well to reef lighting.
So I make a barrier with eggcrate between the Nem village and the frag side. I covered the eggcrate with 1/4" plastic mesh gutter guard on both sides. Effectively this meant the holes should be 1/8" give or take a small amount. Keeping a powerhead just on the frag side meant that I didn't have to worry about Nem soup, but they still got lent of flow from the return. I also covered the overflow with two pieces of the 1/4" mesh. One piece on the front and another behind.
I was Nem proof!
Or not. Got up this morning and three Nems had made it to the frag side. Another was halfway through the overflow and another had made it all the way in. That one got sucked through the outflow when I tried to rescue him. Both parts of what made it through are pretty scrambled.
The takeaway? Any critter made primarily of water can get through double sided mesh and eggcrate even if it's 1/4"
Nems are back in baskets.