Imagine you dropped your keys into the river, you're standing in it, able to see the bottom, looking for your keys. And then your friend John jumps in, and since his impact raised up the sand from the bottom of the river, you can't see anything anymore, so, what did John do? Blurred up the water? Or what do you call this action?
Perhaps "Roil" is the word you are looking for. Albeit, I have never heard this before.
to make turbid by stirring up the sediment or dregs of
The expression I'd use is "cloud (up) the water":
make or become less clear or transparent.
The high winds clouded up the water in area lakes and bays making for tough fishing conditions. — Houma Today
U could use the sponge filter first, as the sand is clouding up the water, because the sponge wont break, and then once the sands all settled then you can switch to the hang-on with no problems! :) — do i need a filter
to muddy Vocabulary.com literal
make turbid “muddy the water”
John muddied the water.
You could say ‘John mussed up the water’. It means to make messy, it includes the idea of ‘roil’, it’s often used for messy hair, it has a sense of movement, with messiness.