Hello,
Have any of you had success removing solid calcium deposits in the HT without removing it?
We have pumped out and washed through thoroughly but he deposits are causing a very slow HT discharge.
Marine TP is now out of the question. With the endoscopic camera I can see the surface of the moon or worse.
We are faithful with the Noal digester and use freshwater primarily but this is a 15 year old issue that has now grown problematic.
I know Hydrochloric acid dissolves this but we wont endanger the ocean.
White vinegar is too weak an acid.
Too date a small hose nozzle at the top under pressure and some tapping (beating) the tank with a rubber mallet is slowly working.
Before I haul it all out for serious backyard warfare I thought I'd reach out and see if any one has had success.
Thank-you, Bob
Calcium Deposits in Holding Tank?
Moderator: KenKrawford
Calcium Deposits in Holding Tank?
Bob & Cherie
Cheeky Monkey - Hull 363
Vancouver, BC
Cheeky Monkey - Hull 363
Vancouver, BC
Re: Calcium Deposits in Holding Tank?
I've used Calgon and boiling water in the past. Yes, the bath product. Lots of people say this works.
More recently, after seeing what Phosphoric acid does for a heat exchanger, I've put this in the hoses and holding tank for a while. A similar product is Barnacle Buster but it's expensive. I bought Concrete and Metal Prep by Klean at Home Depot in the paint department. I ran this through the raw water cooling system for 4 hours. Wow, the heat exchanged looks like new. No more calcium at all. It boils it right out.
So I put it in my head hoping it would help maintain the system and boil off the calcium buildups in the hoses and tank. I ran the head flush pump with water coming in and poured the acid in figuring about a 25-50% dilution. Try putting it in the holding tank for 4 hours and stir it up often if you can.
I didn't have a big problem at the time, so I can't really tell you if this would work that well. But if it is anything like what it did for my raw water system, it might be the answer.
I guess one way to tell if it's working would be to open the overboard discharge after a while and look at the water coming out of the head discharge. If it's white, then it's working.
Bill on TRIUMPH
More recently, after seeing what Phosphoric acid does for a heat exchanger, I've put this in the hoses and holding tank for a while. A similar product is Barnacle Buster but it's expensive. I bought Concrete and Metal Prep by Klean at Home Depot in the paint department. I ran this through the raw water cooling system for 4 hours. Wow, the heat exchanged looks like new. No more calcium at all. It boils it right out.
So I put it in my head hoping it would help maintain the system and boil off the calcium buildups in the hoses and tank. I ran the head flush pump with water coming in and poured the acid in figuring about a 25-50% dilution. Try putting it in the holding tank for 4 hours and stir it up often if you can.
I didn't have a big problem at the time, so I can't really tell you if this would work that well. But if it is anything like what it did for my raw water system, it might be the answer.
I guess one way to tell if it's working would be to open the overboard discharge after a while and look at the water coming out of the head discharge. If it's white, then it's working.
Bill on TRIUMPH
Re: Calcium Deposits in Holding Tank?
Hi Bob,
Luckily I haven't had that extent of problem, my hoses had reduced down to about 1/2" hole by the time I replaced them due to odour. Passing vinegar through them hadn't done anything effective and I had filled the bowl with vinegar and left it sitting in the hoses when the boat wasn't being used. No agitation, no mixing, I imagine the vinegar dissolved a bit of the material in the hose and was then neutralised. Vinegar does a great job of removing a thin layer of calcium carbonate scale off the toilet bowl, but I doubt it is very effective against a thick layer of calcium carbonate mixed with other solids.
I don't think you will do any harm to the ocean if you do use hydrochloric acid, as long as you don't release it in an enclosed waterway, or near fish, it will dissipate very quickly and is just chloride and thus salt once back to neutral pH. Putting several litres of HCl into the tank, keeping the cap off in case you get a lot of off gassing, and going for a long, rough, sail might help break up the solids at the bottom of your holding tank, otherwise it would seem to me that high pressure jetting is the only way you will break up any thickness of deposits.
Luckily I haven't had that extent of problem, my hoses had reduced down to about 1/2" hole by the time I replaced them due to odour. Passing vinegar through them hadn't done anything effective and I had filled the bowl with vinegar and left it sitting in the hoses when the boat wasn't being used. No agitation, no mixing, I imagine the vinegar dissolved a bit of the material in the hose and was then neutralised. Vinegar does a great job of removing a thin layer of calcium carbonate scale off the toilet bowl, but I doubt it is very effective against a thick layer of calcium carbonate mixed with other solids.
I don't think you will do any harm to the ocean if you do use hydrochloric acid, as long as you don't release it in an enclosed waterway, or near fish, it will dissipate very quickly and is just chloride and thus salt once back to neutral pH. Putting several litres of HCl into the tank, keeping the cap off in case you get a lot of off gassing, and going for a long, rough, sail might help break up the solids at the bottom of your holding tank, otherwise it would seem to me that high pressure jetting is the only way you will break up any thickness of deposits.
Russ Peel
Avalon #150
Avalon #150
Re: Calcium Deposits in Holding Tank?
Before recommending anything but a very weak muriatic/hydrochloric acid solution, I would verify with the maker of all valves that could be exposed to it that it would not damage the seals or body.
Said another way, would rather see you pull the tank and hoses than destroy the thru hull valve. I am not saying it would, but should be confirmed.
BTW, boiling out the head exchanger (OFF THE ENGINE) with a 25% muriatic/hydrochloric acid solution and then replacing the end cap gaskets and ZN work very well. Repeat until the boiling ceases/cooling passages are clean.
Said another way, would rather see you pull the tank and hoses than destroy the thru hull valve. I am not saying it would, but should be confirmed.
BTW, boiling out the head exchanger (OFF THE ENGINE) with a 25% muriatic/hydrochloric acid solution and then replacing the end cap gaskets and ZN work very well. Repeat until the boiling ceases/cooling passages are clean.
Last edited by wolfe10 on Sun Jul 25, 2021 5:40 pm, edited 2 times in total.
Brett Wolfe
C350 #180
"Vindaloo"
Ft Myers FL
C350 #180
"Vindaloo"
Ft Myers FL
Re: Calcium Deposits in Holding Tank?
Thank you Gents, great input, much appreciated.
I will make some effort in situ but I probably wont be satisfied unless I pull the tank and inspect everything from top of tank to hull skin.
Going the other way is all new recently.
I will make some effort in situ but I probably wont be satisfied unless I pull the tank and inspect everything from top of tank to hull skin.
Going the other way is all new recently.
Bob & Cherie
Cheeky Monkey - Hull 363
Vancouver, BC
Cheeky Monkey - Hull 363
Vancouver, BC
Re: Calcium Deposits in Holding Tank?
You could use muriatic acid (aka hydrchloric). I’d cut it by 50% first,. Always add acid to water, not the other way around. Let it sit for a while and then top off with water. To protect the environment, go to a pump out station. What you’re pumping out is chlorinated water.. maybe a little stronger than a swimming pool and some Calcium Chloride. Or save the liquid for de-icing your driveway.