How long to empty a holding tank?

Thepipdoc

Thepipdoc

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Bit of a " how long is a peice of string" question .... but as a rough estimate, how long should it take to empty my holding tank on my Sea Ray 270? The tank is 28 gallon and if I let it, which I never do, fill to the brim it would take about an hour to empty?
Have I got a problem?
 
Thepipdoc said:
Bit of a " how long is a peice of string" question .... but as a rough estimate, how long should it take to empty my holding tank on my Sea Ray 270? The tank is 28 gallon and if I let it, which I never do, fill to the brim it would take about an hour to empty?
Have I got a problem?
Click to expand...
A few minutes on the hand pump should do it.
 
Like the others ours takes about 2 mins through the macerator.
Sounds like when you've emptied the tank and flushed it through you should use a hose to fill it with water, then start disconnecting pipes to find the blockage! Good Luck
 
Interesting. Our tank is around 100 litres and I used the flow rate of the macerator pump at a given head of water to calculate it taking around 4.5 minutes to empty. I give it 5 mintues or more usually. When the red light comes on, it takes 90 seconds of running the macerator before the light goes out which sort of confirms my timings.
 
Yeah sounds like you have got a problem. My holding tank is much larger and empties in minutes. Either you've got a blockage in the discharge line or the discharge pump is worn (which does happen because some of the cheaper pumps can't handle larger solids and wear very quickly if run dry). Another possibility is that the seacock through which the discharge pump is routed is not open fully
 
Mike, the pump is new(ish) - I replaced it myself which is how I know the rated capacity, as are all the hoses. It's a little difficult to tell when it's really empty as that would be a three man job - one to drive, one to pump and one to keep tapping the tank, unless we pumped out tied up in the marina or sitting at anchor, neither of which seem very sociable.
 
Agreed. Emptying the holding tank on my boat too is a bit of a hit and miss affair too because there's no tank empty signal, only a tank nearly full/full signal. We stop dead out at sea to empty the tank because thats the only way to see the effluent discharging and know when it stops discharging. Tried tapping the tank but it's quite thick grp and difficult to tell where the level is.
If thepipdoc's pump and pipework is new, then thats a bit of a poser. What about the vent pipe? Could that be blocked causing a vacuum in the tank?
 
Are we talking about an electric or manual pump? Either should empty tank in a few minutes, but if it is manual you can tell when its empty because the resistance on the pump lever will suddenly lighten up as starts to pump air instead of effluent.
 
Thanks - Basically eveyone has confirmed what I thought! I have indeed got a problem.

Is it possible that the problem lies with the outlet pipe from the pump? As soon as it leaves the pump the pipe rises about 1ft and then drops to the level of the the sea cock. If the pump is worn or simply isn't man enough would the short height rise have a bearing on how well it pumps?
 
I think ours is about 150 litres and takes about three minutes to empty. We've got a level gauge but also know when it's empty cause the sound of the pump changes ie speeds up when not pumping anything.
 
Hmmm. This thread is making me think we might have a prob with our macerator pump; it takes several minutes to empty the tank, and the gauge never goes down to zero.

The current pump is a johnson ta3p10-19, and a service kit is available. However, never having done this, I'm told that servicing one of these pumps is on the unpleasant side of yuk and I'd be better off just fitting a new pump. (Especially given that when the boat was delivered, the holding tank was, er, full...).

I'm sure I've read hereabouts recently that diaphragm pumps are much prefered for black water discharge than macerator pumps - any advice on a manufacturer or model to look at? Boat is a Targa 40; holding tank is 200l.

cheers
Jimmy
 
Jimmy

I would fill up with fresh water from the remote emptying point and pump out a few times before convincing yourself its anything more serious. It maybe that the..er..solids were allowed to settle by the previous owner. There are some tank additives that claim to break down any nasties.

If this fails then, its not an expensive job to have the pump replaced.... I had this done recently rather than mess around with a service kit.
 
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