Filter to keep tilapia out of raft grow bed

[Devoid]

I have a raft system based off of the Friendly Aquaponics model. I have had some issues that is leading me to put in filters.

I have two fish tanks connected in series with 2inch pipe, each roughly 352 gallons each that gravity flow out. Current pump is 500gph and I think it needs to be increased.

I was using window screen filter on the outflow but kept having issues with tilapia in the grow beds. When I go to clean it I pull off the filter and immediately stab in a second one. I don't know if small fry or eggs I can't see are going at this point, or if eggs are getting through the window screen. I still end up with thick sludge in my first grow bed.

I removed the screen filter and added in a ~100 gallon swirl filter with intention of turning it into a radial flow later. I've had to medium tilapia make it through the pipes and into the filter. Hopefully I don't have any dead ones in there :/ I now have a lot of tiny tilapia in the grow beds now.

How do you stock fry and keep them from going through the pipes into the filter? If I screen small enough the filter clogs up quickly.

What kind of filter can run over 500gph and filter out tilapia eggs?