Holding tank pump out Bav 30

[Sadlerfin]

Yes another holding tank question.. Please

My Bav 30 has the gravity type holding tank eg open the sea cock and if discharges, (or should do )

ALL my crew are under strict instructions that nothing goes down the toilet unless it's human waste we have a paper bin by the loo. So either my problem is that someone forgot and put paper down it OR calcium build up.

Ours blocked yesterday the standard trick of taping up the breather cleared it, then it blocked again same day and nothing will clear it, the level is now above the inspection hatch so can't get in there

 I can only assume my other option is to get the marina to pump it out. Has anyone experience of this if so if I leave the sea cock open while they pump it out is there a chance that it can suck up or free whatever is causing the blockage? If not guess i will try to get my hand in via the inspection hatch OR remove the outlet pipe from the base of the tank once emptied.

Any other bright ideas will be appreciated. I would say i cleaned the tank last year and it's worked fine for 10 months.

Finally if and when i do clear it I've heard white vinegar helps to keep the Calcium away anyone tried this?

Thanks as always

Derek
Yacht Sa Punta.

[B40-Lefkas]

The pump out is the least disgusting thing you can do and I would start there. If it frees, flush it through with seawater as much as you can.
The buildup is likely calcium carbonate, it can form on the sides of the tank and then drop  down and form a solid blockage. Some people use vinegar to stop the buildup forming but it's unlikely to make an impact on deposits already there - it's too weak an acid.  You can get stronger acids but beware - they will also attack your seacocks. Roto-routers from outside will not help due to the 90 degree bend in the pipe at the seacock.

If the blockage is especially stubborn, less pleasant methods include emptying via the inspection hatch into the shower drain starting a syphon with a dingy pump, or removing the bottom pipe with a plastic rubbish bag to catch any outflow.

Best of luck

[Symphony]

Just a small correction. Acids will have no effect on your seacock.

[Sadlerfin]

Thank you

Just going to be an interesting experience .

Boat ownership, I love it.

[dawntreader]

Try to force air - foot-pump or compressed from cylinder - up the 'out' vent from the outside of the boat. This should lift the debris and allow the holding tank to clear. About 10 second bursts will help. Things to note:

• If you use a hose to pump air up the vent, a cloth is handy to provide extra sealing
• Don't block the breather when doing this but keep clear of it too 
• keep well back from the outlet - when it goes, it goes 
• Once clear and flushed, get a camera into the inspection hatch and look to see if you have calcium debris inside
• If you do find debris, remove it by hand. A long plastic bag taped up to your armpit will make this less unpleasant