sludge in marine holding tank

[keith c]

Any ideas how to remove a 3 in layer of sludge from my black water holding tank? Hope Peggie is listening !

 

[Comodave]

Ted, OC Diver posted a little while ago on how to clean the holding tank.

 

[Bacchus]

Here is Ted's thread.
https://www.trawlerforum.com/forums/showthread.php?t=46357
He has added that a week or more soak time and agitation recommended.

 

[HeadMistress]

Any ideas how to remove a 3 in layer of sludge from my black water holding tank? Hope Peggie is listening !

Removing sludge buildup is NOT the same thing as cleaning the tank. Unless it's turned to concrete, it can be easily flushed out:

After pumping out the tank put at least 6" of water into it via the deck pumpout fitting--cuz that sends the water into the tank at the bottom to stir up any sludge and hold it in suspension so it can be pumped out...repeat, repeat until you're pumping out clean water.

Alternatively if you have a washdown pump and the ability to dump the tank at sea, head for open ocean at least 3 miles from the nearest point of land and use the washdown pump to add the water: stick it into the deck pumpout fitting and let it continue to run after you've put enough into the tank, then open the thru-hull, turn on the tank discharge pump,and let the water run until it's dumping clean water.

To prevent sludge buildup, do this 2-3 times a year, advice I've posted here many times.

--Peggie

 

[Easternshore]

Try this for breaking-up gunk in your holding tank. Open the deck pump-out fitting and dump a 10# bag of ice cubes down into the tank. Take her out for a spin, the rougher the ride the better. To help “rough up the ride” go in circles over your wake to bounce the boat, the ice cubes will bounce around inside the holding tank and help break up the gunk. The following day pump out the tank as the cubes will have melted.
Repeat again if needed.

 

[Bacchus]

Try this for breaking-up gunk in your holding tank. Open the deck pump-out fitting and dump a 10# bag of ice cubes down into the tank. Take her out for a spin, the rougher the ride the better. To help “rough up the ride” go in circles over your wake to bounce the boat, the ice cubes will bounce around inside the holding tank and help break up the gunk. The following day pump out the tank as the cubes will have melted.
Repeat again if needed.

Google ice cubes for cleaning RV holding tank and watch the videos. Simulated (plexiglass) tank mounted in back of a pickup show VERY LITTLE cleaning action from the ice... even when it's driven like it was stolen.
Sodium percarbonate is my new go to treatment and very satisfied with results. A few flushes until discharge is clear is also a key.

 

[Pura Vida]

FYI

 

[Comodave]

I don’t see how you could get a 10 pound bag of ice down the pump out hose anyway. It will just stack at the bottom of the hose until it melts. If you have the dip tube pumpout in the tank the ice won’t be able to even exit the dip tube. It will not make the turn and plow into the tank as ice. And after it melts it isn’t going to do anymore scrubbing than the water it will turn into. So unless you have an access hole in the top of the tank there really isn’t a good way to get ice into the tank. I think I would go with the chemicals.

 

[Easternshore]

The cubes are smaller than the opening, naturally you’re not gonna dump the bag in all at once, they go in one at a time. Drop the bag on your dock a few times to break-up any large blocks of cubes. It should be a rather clear shot to your holding tank. This has been recommended on sailnet for years, some suggest adding liquid fabric softener.

 

[TowLou]

As Peggy mentioned, toss some water in there and shake it up. That's how I get the sludge out of a tank minus the shaking. Shoot some fresh water in it and suck it back up.

 

[Easternshore]

As Peggy mentioned, toss some water in there and shake it up. That's how I get the sludge out of a tank minus the shaking. Shoot some fresh water in it and suck it back up.

[emoji1360]