Snow globe?! Help!

[.Haliax.]

Turned my return pump off for quick feeding/maintenance… Turn it back on and my tank looks like a snow globe! Anyone tell me what this is? TIA

 

[Adrift]

Hmm will be following to see answer

 

[ying yang]

I get same problem everytime I do a water change and turn return off then when turn return back on my dt gets lots of what looks like molts from pods.
I'm guessing it's what gets through my sponge on pump and stuck in pipes and what not then as power on pump comes on with force it clears the pipe so to speak.
But that's just an educated guess on my part.
I've started putting a net in front of return nozzle to catch it all when turn back on.
Should really take flexible return hose out and clean it but don't want run risk of causing any problems and not being prepared lol so I just leave it.
Be interested also to see what others say