Just woke up to a sucking sound coming from the tank...

Yeah, and it always happens at 3 a.m.

 

If problems happened at times that were convenient, this hobby wouldn't be nearly as exciting!  ;-)
For a snail guard, drill some holes in two PVC end caps and enclose your float switch in that.  I think 1 1/2" is the size that will fit most float switches.  You can then attach it to whatever you mount it to in your sump using a zip tie tie attached to the inner PVC pipe itself (not the end caps).  If you cut the inner PVC pipe to length just right, there will be just enough room for the zip tie to fit, so the end caps will hold it snugly in place keeping it from sliding on the zip tie.  When I do this I usually end up cutting it a little too long, fitting, measuring how much additional to cut off, and then making a second cut to make it a perfect fit.  Does that make sense?
--AJ

 

A snail got in my drain on my frag tank. In the end...I no longer have a frag tank. I broke the back of the 40b cutting into the pvc. There are at lest 3 lessons learned here but I would still have a tank if that snail had not crawled in there!

 

I fought with this on my frag tank for a while, then bit the bullet and bought the strainer/gaurds. They were like a dollar each, I was pretty mad at myself for not doing it much much sooner.

 

Something like this:

http://www.bulkreefsupply.com/store/products/pumps-and-plumbing/plumbing-sumps-drill-bits-overflows-uniseals/bulkhead-tank-adapters/bulkhead-strainers.html