Obviously I wouldn't wash my hands and then immediately put my hands into the fishwater, but I've washed my hands less than an hour before putting them into the fishwater numerous times and my fish have never showed any symptoms of chemical poisoning. As long as you thoroughly wash the soap off, the amount you introduce into the tank is negligible, if any at all.I don't do this personally because I've never had any problems just putting my hands right into the tank, but if you're worried I suggest scrubbing your hands/arms in warm/hot water beforehand. I wouldn't recommend using soap before putting your hands in the tank though, that may bring over unwanted chemicals
My hands/arms are frequently in the tanks. No ill effects so far. I just make sure there's no lotion or soap residue. As for algae scrubbers, one day, I took a lumpy (my fault) Marimo Moss Ball and used it to clean the inside walls of the bio-film stuff. Much less pressure is required and they seem to do a better job. I just rinse them out in the sink and toss them back in the tank. I have two African Dwarf Frog tanks and they prefer the smashed up and flattened moss balls to hide under, rather than the balls in their ideal, round shape. So, I've started to use Moss Balls to clean the walls in all tanks!Can I just reach into the tank and scrub the inside glass. Or does my hand impart anything bad into the tank and I should use one of those magnetic scrubbers?
It's funny the things you discover by accident. Today, I did a partial water change, then turned off the the kitchen faucet and disconnected the hose from the faucet. Suddenly, I discovered that the hose was siphoning the water from the tank. I couldn't understand until I realized that the end of the hose in the water was directly, unintentionally, above the 40g air pump! I can't explain it any other way, so I'll stick with that theory and will practice next week.Nice Tip!