brucebollert Report post Posted July 7, 2017 I'm a newbie with a 25' Sun Seeker MBS. I was told when I bought the motorhome that I should wait until black tank is 3/4 full before dumping. I have been out a couple of times and the tank is now 1/3 full. The coach will now sit for a couple of weeks. Should I wait until the tank gets 3/4 full or should I dump it now? I'm sure this topic has been discussed somewhere on the forum. Share this post Link to post Share on other sites
rossboyer Report post Posted July 7, 2017 Dump now. Don't wait that long between dumps. Share this post Link to post Share on other sites
wolfe10 Report post Posted July 7, 2017 I agree. And, best to add some water to the tank (tank flush if you have one or even hose into the toilet. Like Ross, I would not store a coach, particularly this time of year with 1/3 full black tank. Share this post Link to post Share on other sites
rayin Report post Posted July 7, 2017 There are several different things to consider in your particular instance. Waiting until the black tank is 3/4 full in good advice, in your circumstances you might be slowly building a pyramid of solids in the tank when it is allowed to sit partially full-unused for weeks/months. You will flush the tank better if you fill the tank with water to 3/4 then dump. After dumping add a few gallons of water so it's ready for your next outing, and the seals stay wet. Share this post Link to post Share on other sites
mweiner Report post Posted July 8, 2017 In 100 plus degrees heat?? I would definitely dump the tanks...you can add water later or soon after, but, what's the point in waiting.. add some water to the black tank by just flushing the toilet or adding packets for sanitizing and fresh smelling ingredients... camping world sells lots of these.. handy. Share this post Link to post Share on other sites
manholt Report post Posted July 8, 2017 When I'm in a campground, I dump mine between half to 3/4 full. Gray at 3/4+! I like having full gray when I dump Black...On the road my tanks are empty, except for about 50 gallons in fresh water tank and when I park in my garage, I have empty tanks and full fuel tank! I don't throw any Camping World packets in my black tank ! Share this post Link to post Share on other sites
hermanmullins Report post Posted July 8, 2017 One thing that might help is a Holding Tank Flush. If you have access to the side of your tank you can install a flush attachment to your tank. Then when you are home you can drain your tank and flush it completely. They can be purchased from most RV supply stores. Herman Share this post Link to post Share on other sites
brucebollert Report post Posted July 8, 2017 Thanks all for your advise. I'm filling the tank 3/4 with water and heading to a dump station.. Share this post Link to post Share on other sites
desertdeals69 Report post Posted July 8, 2017 23 minutes ago, brucebollert said: Thanks all for your advise. I'm filling the tank 3/4 with water and heading to a dump station.. I would install a clear section on the dump hose so you can see when it is flushed clean. I am at a campground in Mi right now and had to change my dump valve which was 15 years old. It took me 6 flushings of 1/2 full of fresh water to get the water in the dump hose perfectly clear before I disassembled the valve. Share this post Link to post Share on other sites
