Holding tank mods

[essexboy]

I have a 50 gallon holding tank, which I need to clean out. I want to fit an inspection hatch into the tank to wash it out with a pressure washer. This I know has all the makings of a disaster ! But my first problem is the tank is made of GRP and does not have a flat surface. Will the standard screw in hatch about 100mm diameter, take a small bend and still seal ? Will I regret even thinking about this ? Will it end up on UTube ?

 

[P4Paul]

I have a 50 gallon holding tank, which I need to clean out. I want to fit an inspection hatch into the tank to wash it out with a pressure washer. This I know has all the makings of a disaster ! But my first problem is the tank is made of GRP and does not have a flat surface. Will the standard screw in hatch about 100mm diameter, take a small bend and still seal ? Will I regret even thinking about this ? Will it end up on UTube ?

Build up a flat surface with GRP then cut out the hole.

I think a YouTube clip of you pointing a pressure washer into a holding tank is absolutely required, please paste a link on here after you have cleaned up the mess!

 

[jrudge]

What problem are you seeking to solve that won't be resolved by flushing with holding tank cleaner ?

 

[jimmy_the_builder]

Depends how not-flat it is. I fitted a TCL-4 hatch to mine with loads of sealant, and it's been fine. The surface that I mounted it on is flattish, but by no means perfect.

That said, jet washing the inside of your holding tank does sound like a recipe for disaster. Like jrudge asks- what's the problem you're trying to solve?

 

[essexboy]

When we bought the boat it had been left for over a year with a full tank ! And I mean full. We have had is drained and flushed but sometimes an " aroma" greets us, so I intend to clean it squeaky clean, improve the ventilation, what could possibly go wrong ! Having said that £500 for a new tank seems increasingly like a good plan B.

 

[jrudge]

I doubt a tank clean will solve that. It smell is getting out you need to resolve that issue

Pipes can smell and need replacement. A carbon filter may help. Once you clean it out it will get full of pongy stuff again so you need to resolve the underlying issue.

 

[jimmy_the_builder]

I doubt a tank clean will solve that. It smell is getting out you need to resolve that issue

Pipes can smell and need replacement. A carbon filter may help. Once you clean it out it will get full of pongy stuff again so you need to resolve the underlying issue.

Yet again I am in violent agreement with jrudge. It won't be the tank, it'll be the pipes. Ask lanerboy about replacing black water pipes, he really likes doing that job

 

[wingless]

The holding tank on my Vacuflush system has a level sensor. It has three floating magnetic switches that slide up and down 1" at the end of different-length semi-rigid plastic wire tubes.

These tubes are attached to a 4" screw-in fitting, w/ a mating fitting on the top of the tank.

When I clean my holding tank, I pump out, remove this level sensor, then use a garden hose and a long bottle brush and powdered cleaner.

The end result is that the translucent white tank walls are maintained to be clean enough for visual inspection of the tank level.