Sorry for the loss but thank you and your boys for being such good neighbors. I misunderstood that you still have fish in the tank so...........yes scale back the water changes to 10-20% every other week just check the specific gravity of the tank water, match it and water temperature. You can siphon off the nusisance algae and dirt for the water changes. If the salinity is off, should be 1.22 - 1.25 just increase gradulaly with the water changes, best to go slow a little at the time and more often than trying to make a big change at one time. What you can do is run a filter on the tank such as a Fluval or Ehiem that you can get at Petsmart or such this will also help to clean the gunk out of the water as it is stirred up. Hey, don't give up, it can be done. Let us know how it is going when you can.