Tragic Sea Hare death
 

Hi there, My Sea hare, has had an untimely and tragic death. He made his way through the top grid of the overflow, and got sucked into the screen leading to the sump. This tested the "herbie style" overflow for the first time, and it worked, very well! preventing a possible flood. I'm sure glad i took everyones advice and made the change in design of overflow. Should i be concerned about toxins in the water? The lights were out, and couldn't really tell if anything bad was released. I've prepaired water for a water change just in case. Always seeking advice and comments on how to Sea Hare proof my overflow. Sea Hare.....R.I.P.

I don't think its possible unless you use small mesh or enkamat to cover the top. Those slugs will try to go through any holes. I had one that got stuck in eggcrate when it tried going through a .5 x .5 square not realizing that its big butt is about 2"x2" big - kinda like the Santa Claus dilemma.

Zip-tie some gutter guard over your eggcrate overflow top to help keep snails, hermits, fish and anything else out of the overflow.
You can pickup a roll at Home Depot or Rona for a few dollars.

You can also zip-tie on the plastic background matting used for needle point. You can find the sheets in the sewing section of wal-mart, the sheets are about $1.00 each. It works very well for not letting small fish/snails etc. to go through the overflow, however it does reduce the flow and needs to be cleaned often.