Greetings, ....nylon window screen....Please don't do this to your plants !
I did it and regretted it. Here's why. Those nets are NOT going to stop ROOTS.
Again, roots in water, especially hydroton ( medium ) hydroponics water, are not in danger. What happens with the addition of a mesh screen is,
it collects decaying matter, nutrients and rotting wants a piece of the action.
The addition of a mesh screen blocks the fafaflowy of the water and
nutrients, so you might wanna consider flushing with the pH, treated water.
Water that has a pH. around the high 5's to 6ish. Once the drain water,
pH. stablizes around those #ers ( 5 - 6ish ) then go back to the
nutrient schedule you have going.... But the flush idea is the most
important function of this hydrosystem...
I'm thinking of building something, that attaches to a pump / suction
to the drain / fill hoses, of the ebb & flo sytem.
But for now, i just keep my attention to the pH, PPM's and all the basics.
I have switched to the HPS setup for this flower phaze !
" She wore Lemon " as they say !

pH balanced,
Zee