BettaFishMommy
finkids make me happy :-)
instead of disturbing the plecos just move the rock over to one side of the tank and change the gravel out on the empty side. when done, move the rock over to the new sand side and repeat on the other side of the tank. as long as the plecos' hidey hole is always underwater, you can do a few water changes during the process to keep the tank from clouding up too much. this worked for me on the few occasions i've had to change substrate.