What is this?????

[Ronnell]

Hello all I am new to this BUT I am not. I have been wanting to do this for over 5 years this year i did it. I am in my 5 or 6 week of cycling LFS says that my lvls r good, so as I looking to find a way to hook up my maxi-jet 1200 as a pump in (for) my sump and I noticed this on side and this

On the other side

is this normal or should I worry about it.

 

[Crabs McJones]

Looks like normal sandbed detritus build up this is why if you dont stir up your sandbed regularly, and you switch tanks, it's best to use new sand
All this trapped stuff gets released into your water