Been thinking of an easy way to add a bottom drain for my little goldfish pond. Really didn't have much faith in it working so I didn't take pictures of the making of lol. I spent zero money on the project, just used some junk out of the shed along with some epoxy and loctite construction adhesive that I already had.
First I took my strainer off my submersible pump. Then I found an old black plastic flower pot in my shed, think I got it a couple years ago at Walmart for 1.98. Then I traced the size of my pump strainer on thebl bottom of the flower pot, which was just a bit smaller than the bottom of the pot. Used epoxy to set the strainer in the hole I cut out in the bottom. Then sealed it off with the construction adhesive. Then I made 5 small legs out of half in pvc and used adhesive to set them in the pot so the pot sets about a quarter inch off the bottom of pond. Finally I used the adhesive to attach rocks on the inside of pot for some weight. The pump the just attaches to the drain like it would to the strainer, guess you could day I modified my strainer into a retro bottom drain.
As mentioned before I really didn't think it would work all that well, but I hooked it up, had to do some running and came back to see a pretty clear pond bottom. Actually had to pull it up and clean out all the string algae it sucked up. This is gonna really work well and save me quite a bit of trouble. Didn't take pics of the making process, but took one of it in action after I realized it was a success.