ask your lfs they usually have them behind the counter, with bulkhead kits.
if not search online for bulkhead slipscreens! DO NOT use end caps it will slow flow to much leading to probs, until you slipscreens. an old fish net would be better.
do not go with 2 inch as it would be to bulky and overkill, i dont think i would use that on a 400 gallon.2x 1 1/4 would be perfect, 1 1/2 would also be overkill.
also make sure to put elbow on drain like in pic. keeps it alot quieter.
also an endcap on vent pipe,makes quieter.
someone here recently( like yesterday posted plans ). these are plans i have passed on in the past. just dont forget elbow on drain, and end cap like they did.
also i live in florida, sometimes we go without power for hours and somtimes days. this happens all the time. and these guys start up every time.
when your ready to start this let me know, i have more tips!!!