Sand sifter in gig tank / general help

[tufacody]

I started a 70 gallon tech tank with a gigantea about 6 months ago. It is plumbed into my 300 gal system. I used the special grade substrate for this tank. There are a variety of snails.

Yesterday to my surprise I noticed that the sand had become like concrete. It crumbled in my hands with some effort, but I broke it all up again.

I assume this happened because of kalk dosing? Apparently my snails aren't doing well enough going thru it. So now I need a critter that won't get eaten by the gig or disrupt my spawning clowns. Any ideas how to stop this from happening in the future?

 

[jmadison]

a diamond goby would turn your sand over frequently. I have heard of people having hardening of the substrate issues due to dosing(or so they deduced).