A few questions before i do a good revamp to my tank! Hope you experienced people out there can help me out, thank you for reading and giving your opinions.

I was thinking of using Gex soil to fill up the gaps between my gravel, will it be ok? Because right now, my leftover pellets are getting very irritating to my eyes as my gravels are white.

I read it somewhere, such soil will help dissolve my leftover pellets, is that true?

I have a crayfish in my tank, will the soil be harmful to him? He is the reason why i started having a tank.

I chose Gex instead of ADA because ADA will start to cloud the water after few weeks, read it from here.