It was still sunny when I got home this evening so decided to try and get rid of the worms that had been showing up occasionally around the rim of the tub. Don't have a worm family pic but they were about an inch long at full size, black, segmented, and seemed to be living between the top rim of the tub and the cover. Also saw small black dots which I took to be eggs.
The cover is aluminum behind the stove fence (normally doesn't ever come off) and 2" cedar in front of the fence (which comes off when I'm using the tub or testing the water).
I had been under the weather a bit for the last week and noticed the water was getting a bit cloudy, so figured I would SLAM rather than draining & refilling, and take advantage of the high FC levels to try and repel boarders from the worm community. If I was going to SLAM I figured I needed a better way to hold the hoses from my filter/pump underwater so I could safely leave the pump running without worrying about the hose ends flipping up out of the water.
My plan was to fasten the jet/strainer fittings to the ends of the hoses, then tie a weight to each fitting and use that to hold the hose end under water. Spent some time trying to hose-clamp the fittings into the hoses so they wouldn't slip out (slippery hose plus slippery tapered fitting plus really cheap hose clamp = frustration) -- then finally realized that I didn't need a leak-proof connection because the fittings would be underwater anyways so used a couple of sheet metal screws instead
OK, that worked -- next revelation was that the hose & fitting sizes were just what I needed to wedge the fittings under the edges of the benches, so now I can clip the hoses in and start pumping in literally seconds. Once I got the pump running I raised the FC to SLAM level, let it run for a bit, and then started de-worming the top of the tub. Nothing fancy, just removed all of the covers (including the aluminum ones in the back), flipped all of the worms and eggs I found off into the forest, scrubbed the top of the rim with high-FC water from the tub and let it dry, and repeated for good luck. Also scrubbed the edges of the covers the same way.
Ran the pump for a few hours tonight, will do the same tomorrow. Having a reliable hookup for the hoses sure makes things a lot easier.
I suspect the worms moved in back when I was using more copper and less chlorine in the water, and then survived between the rim and the cover because the water there would all be condensation and so probably chlorine-free, which leads to an obvious question -- are the maintenance FC levels recommended for bacteria and algae control also sufficient to prevent worms & mosquito larvae from growing in the water ?