So there have been DIY threads on retrofitting strainers but after recently spending some time with Lodo I can confirm another ready-made solution.
For a while we have had these Pro Mesh Filter guards available. The image below is the long version, 14cm.
Lodo has designed a setup great for his tanks. I had the following concept.
Just using the plumbing tape you use to seal threaded joints, you wrap around the open end. Once you've got enough on you can twist it into the female threaded section of your bulkhead. No shrimplets getting through this baby!!
And the beauty is, due to the length, it has a large surface area open to the water, even if leaves collect on part, there should still be adequate water flow. Oh yeah, it's open on the end too.
These are available at site sponsors now! At least, I know I stock them! I think Aquakitz too!
Hope this helps! It seems such a simple solution!!