Black water tank

Peg_O_My_Heart

When I have the marina pump out my tank, it collapsed at the end of the process.  It returned to its shape after the pump was removed.  I have read this could be a blocked vent.  Any suggestions on how to fix that problem?

Black_Diamond

The vent could be blocked, more likely the person was to aggressive with the sucker; they are using a 1.5" hose vs your .5/.625" vent line. Losing battle.

For $40 add one of these, takes 5 min to install:
http://www.ardemco.com/sealand-313255247-tanksaver-holding-tank-relief-valve/

Peg_O_My_Heart

thank you for the quick response

Michael T

I have a waste tank safety valve that is 3" in diameter, as well as a small relief valve that came with my Big Orange filter. Still, I was surprised by how much my tank was "sucked-in" during the pump-outs and I could hear both safety vents whistling. Last summer I was at a marina and the dock boss came up to the teenager who was pumping out our waste tank and said "You're using too much vacuum, let me show you how to adjust it."  Most damage to waste tanks, other than age, is due to the use of too much vacuum. The $40 waste tank safety relief valve is probably the best insurance you can buy for your boat at that price. That and a Big Orange filter or like Tiki designed, a quality home-made charcoal filter. MT

srlaman

I bought one of those vent relief valves and it still sucks my tank in.  I have to pull out the valve which helps to keep the tank from collapsing.

Dream_Inn

srlaman said:

I bought one of those vent relief valves and it still sucks my tank in.  I have to pull out the valve which helps to keep the tank from collapsing.

Same here. 

davidbrooks

So one word of caution.  It is likely fine.  No cracks or issues, however i would recommend pulling it out and inspecting it.  I had a loose fitting on mine this summer and the cleanup was a mess.  

rasbury

I had a hole in mine...never did figure where it came from...about 3/16 , was not threaded or anything...like someone drilled it in a spot accessible but hard to see...

kordo

My process is to push the foot peddle down and set the button on the peddle to keep the ball in the bowl half open as per the instructions and then open the engine hatch and watch what happens to the tank while it is emptied.  If there is an issue with it collapsing, I can tell the attendant to stop.  I have the tank saver and it opens when the tank is almost empty.  Works fine, this is after I replaced the tank due to PO allowing it to collapse and develop a crease that was sure to rupture and ...