Re: [Amel] Re: rear holding tank clogged

Ian Shepherd

I would be very careful in using any acid in your holding tank. The
parts are NOT all non corrosive. The connecting pipe between the bottom
of the holding tank and the down pipe to the valve is made of thin
walled copper pipe. Why Amel chose to do it this way is puzzling. I had
a disastrous leak from this pipe without ever having used acid in the
tank. The copper was completely eaten away by corrosion from toilet
waste, sea water etc. I have now replaced this vulnerable pipe with
pipe made out Teflon with double O-Rings so the failure should never
happen again. I have also converted my toilets to fresh water successfully.

Furthermore, I can now use acid as described by Bill Rouse with
confidence. It does free up the ball valve for a while but as Bill says,
use it only for a few seconds then flush through thoroughly. I have
tried pouring a mixture of Corrosion Block (Corrosion X) and olive oil
onto the ball valve through the deck pump out access afterwards. It
helps a little.

One of the good points in the design is that the deck fitting and the
holding tank exit pipe are vertically in line so it's easy to rod
through. I found a larger sized shroud cover useful for doing this. Use
a spare one and not one off the shrouds else it may break if its been in
the sun a while.

Good luck!

Ian Shepherd SM2000 414 Crusader 2003 Thassos Aegean

On 30/07/2013 16:08, sv Sangaris wrote:


I may have been the one you recall being an advocate of Hydrochloric
acid - also known as Muriatic acid. All your plumbing parts will be
non-reactive with it (remember, much waste going in is acidic).
Depending on the amount of build-up in your pipes you may have to let
it "cook" for a long time and repeat to get them really clean. Then
every few weeks should keep things clear. No need for the extra
chemical reaction excitement of adding a base like baking soda to the
acid - the deposits you're attacking are already doing that so just
flush everything through. Hydrochloric acid totally dissociates in
water. Of course, do be eco friendly with your discharge.

It's sold in many countries as toilet cleaner, but read the label to
be sure it's Hydrochloric acid and not caustic soda and never mix
those - way too exciting. Some brands also contain surfactants that
add to the effectiveness, but plain HCl is excellent and cheap.

Craig Briggs

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