Maintenance of Holding Tank

[dawntreader]

[I've created a new topic as this one was buried in the 'skin fittings' item].
I have been having increasingly difficult times with my holding tank not clearing properly (or not at all). This was usually remedied by forcing water or compressed air into the outlet with the valve open and moving back quickly. This is no longer working and I can only conclude that the inside of the pipework is calcified to the point where movement is severely restricted. I had decided to take the boat out and replace the outlet pipe and seacock. However, I received the following advice from Lazy Pelican [John] :

"I had a similar problem. It wasn't the pipe work which caused the blockage - I'd replaced this when changing the sea cocks (to Trudesign ). The problem was that huge amounts of calcium had built up on the inside of the tank and slabs of calcium fallen to bottom of the tank blocking it.
We were midway thro a cruise at the time. My solution was to open the access hatch and manually remove as much of the crud as possible, aided by periodic flushing the tank thro with a hose. It's a horrible job but I ended up with a bucket full of calcium and a tank which emptied -no problems 2 years on.
I'm not looking forward to doing the same job on the ensuite!"

I opened my access hatch and found the same problem. The calcium had built into slabs up to 0.5 inches thick and these had fallen off the walls of the tank and blocked the (relatively) small 38mm outlet pipe. So where previous reverse flushing had cleared the layers and allowed a flow, it was now blocked to the point where manual intervention was the only practical solution as the crud was at least 4 inches deep. You do not want to do this job twice! Without going into the gory detail the header tank is now 'clean' and empties immediately.

The problem appears to be caused by the fact that external  flushing does not clear all the debris and nor did the use of 'chemical toilet additives' prevent the build up of calcium. I am resolved to opening the access hatch for an annual clear out but also intend to try cleaning products specifically used to treat calcium - the first one that came to mind is CalGon used in washing machines which I hope will not damage the system components. However, any advice is always welcome.

Jim

[Moodymike]

I think the title needs changing to holding tank.   I had a similar experience last season, caused by calcium blocking the valve. Managed to clear it with a pressure washer and drain clearing attachment ( thin tube with sprung spray end). By reaching down into the tank was able position the attachment down the exit tube.   Took some time but did clear it.

[Aquila]

I never realised calcium build up was a problem with salt water, I could imagine a salt residue but never considered calcium.  If this is the case as you say it needs some form of calcium eating product.  My experience on my previous Bavaria 31 which often blocked was all based upon paper fibres building up.  Needless to say on Aquila nothing goes down the head unless you have eaten it first, thank god for nappy sacks.  Sounds a pain but we have never had a blockage ever since.  Thanks for " "heads up" (sorry) though and I will check out calcium levels!!

[Ziffius]

Had the aft holding tank block last year with calcium. Of course we had guests using it and it was near full - eventually managed to get enough out using the compressed air from a fog horn to be able to open the access hatch. My guest offered to put his arm in but I said no - only to find my arm is too muscular to fit through far enough to poke the rod about. Good thing the wife was aboard!!

Having seen how much calcium there was I decided to poke about the forward tank at the end of the season - that was just as bad. Word of advice, if you are poking about with a rod, make sure it is tied on with a length of string in case you drop it to the bottom. Because I couldn't get my muscles all the way in I vouldnt reach the bottom to retrieve my rod. Unfortunately I was solo this time so the wife couldn't hear the expletives coming from the heads.

Also took off the toilet to tank pipe on one and bashed it about to clear out the calcium from it. Amazing how much there is. I want to do the other heads pipe but haven't managed to release it from the top of the holding tank - calcium seems to be a bit like cement!!!

[njsail]

This might sound crazy but a few years ago when i replaced all the sanitstion hoses i removed the holding tank relatively easily and took it outside and wahed the insides out thouroughly.  Bavaria makes it really easy to do that.  The access hatch pops off and 4 bolts later your cleaning the tank.  After the hoses went back on the tank is now pristine clean.  It wasnt a fun job in any way but try doing that on a boat from another manufacturer.  Once we did the hoses and tank there was no more head smell and that was the goal.   I donfeel the GRP plastic holding tanks are much better than aluminum inhad in orior boats.  When the head plugs up everybody is unhappy.

[Aquila]

Thinking more about this I have seen on the Clipper Challenge boats the pipeline has had so much calcium in the pipe the hole was down to millimetres, mind you the length of the discharge pipe is about 6 meters long.  The answer was to change them every so often.  So as said earlier maybe it's well worth checking pipeline and cleaning or replacing.

[Ziffius]

Njsail not sure it's possible to remove the tanks on my bav 39 - isn't think the hatch is big enough to get it through.

[njsail]

@Ziffius - I only mentioned because often all the ideas being shared by the group make me think about alternate ideas.  In my case I was shocked it could be done so easily on the Bavaria Ocean 40...never seen anything like that setup.   In the end...clean pipes that don't stink and a tank that let's the head dispose of its load is all that matters.  I think I'll go say hello to my boat this week....she's been covered in freezing weather and I miss her

[Happy Sailor]

Have had similar calcium problems in the past with our 2005 33C. but no longer! A gallon of "brick acid" from builders merchants (must be the version containing acid not the non acid one) mixed 50:50 with water in the pan. Sucked into the pipework and tank, and left for a few hours (overnight if bad). You must loosen the tank emptying cap on the side deck as gas will build up and needs venting. Environmental disposal of the spent liquid can be a potential issue so we do ours every two years when ashore, but worth the hassle as it works well. Flushed well afterwards and no obvious damage to fittings.

[Nigel]

Discussion of charcoal filters moved to new thread.

[Jeffatoms]

We are the proud new owners of S/V Zephyrus, a 1998 Bavaria 38 Ocean. The boat has been well used ( sailed from Seattle to Baja and back earlier in life) but also fairly well cared for.  We just learned that the sanitation hose leading from head diverter valve to the holding tank is 100% blocked such that the Raritan manual head actually pressurized the line.  Seems like the right thing to do is extract it out from the head, leaving the diverter Y-valve attached but closed and duct taping the new, replacement sanitation hose as it's own messenger, sealing the storm within...within.

I can see where the hose drops from the top of the holding tank to the floor of the bulkhead behind shower, exits the engine space and appears to follow a channel-chase under the shower stall but I fear it disconnecting "mid channel" and dumping it's waste in the most inaccessible spot on the boat.

Wondering if there is good advice from a fellow Ocean 38 owner whom has shared my dilemma, my fear and overcome the challenge?  Also, how long is the hose so that I am sure to attach enough if that is the way to go.

Thanks in advance!