Another Heads cleaning question

[RIN]

Our heads have been going pongy. Not the pong you get when you get down to the boat which disappears when you have flushed the seawater through the pipes, but one that we found out is coming from the shower sump.
We never use the shower on the boat but It looks like the action of the boat is forcing seawater back through the shower sump pump into the sump - not much but enough to go pongy if left for a few days.
Unfortunately the drain hole for the sump is slightly above the bottom of the pump so it does not have a chance to drain out.
Its also a bit baffling in that I assume the hull fitting is above the waterline

Now does this mean something is going wrong with the pump? should this happen? Anyone else had this experience?

 

[JerryC]

Have you checked that it really is seawater? On my P40 the showers and wash basins all drain into the sump box. Also the pumped outlet and vent hoses loop WELL above the skin fittings which are about 6 inches above the waterline, so I can't imagine seawater flowing back into the sump box.

 

[Momac]

Try a toilet bloo block in the shower sump box. Or pour a little Elsan Blue down the shower waste.
I use a little clean water and a splash of Elsan Blue in the toilet pan when leaving the boat. This very effectively kills odours from the toilet.
.

 

[Andrew M]

I've had great results with loo and shower pongs using this :
https://www.plumbworld.co.uk/saniflo-cleanerdescaler-5l-101344-29422

But have also recently found this which I suspect is basically a very similar stuff but much cheaper:
https://www.hygienesuppliesdirect.com/products/prod234305-4x5-litre-toilet-macerator-descaler