How to descale a 300l fresh water tank

[CaptainRivet]

Hi all,
My 2 water tank">fresh water tank, each 300l, need to be descaled. Is Yachticon supercleaner working?
Or What else can I use for that? Should be high concentrate stuff that is freely available. I am in canary islands. Obviously its not practical and manageable to get 600l vinegar.
Replaced the pipe that connects the 2 tanks and the 2 valves where completely scaled and seized in that white pest and the pipe had big chunks of scale in it. Plastic valves in vinager for 2 days came out like new and working... But how to get 300l tanks descaled? On the dry dock right now, will connect a 1,5" pipe to the tank and pump it directly out with a big pump as big chunk of scale will come out for shure so i don't hav it in the boats pipes.

[sailorboy1]

Any acid should do it. The amount needed depends on the amount of scale. You are going to have to flush the tank pretty good after.

[Pete7]

Do you have inspection hatches in the tanks?

[tkeithlu]

Sailorboy speaks with wisdom.

Is the tank plastic? The admiral/consulting chemist is hesitating to make a recommendation if it's aluminum. Stand by...

Here: Largely fill the tank with water and then add muriatic acid to about a 1:10,000 concentration, looking for a pH of about 4. That emulates vinegar. Do that in steps - don't pour the concentrated acid directly into the tank. Always pour acid into water in your mixing container. Be very careful - it's pretty vicious stuff.

Then, let it sit for a few days. That will soften it up to be flushed out.

Concentrated muriatic acid will descale your tank in seconds, and then digest your engine.

Muriatic acid is used on cement decks and swimming pools. Here's an article on its safe use:

https://www.bobvila.com/articles/muriatic-acid/

Good luck with it.

[CaptainRivet]

Originally Posted by tkeithlu

Sailorboy speaks with wisdom.

Is the tank plastic? The admiral/consulting chemist is hesitating to make a recommendation if it's aluminum. Stand by...

Here: Largely fill the tank with water and then add muriatic acid to about a 1:10,000 concentration, looking for a pH of about 4. That emulates vinegar. Do that in steps - don't pour the concentrated acid directly into the tank. Always pour acid into water in your mixing container. Be very careful - it's pretty vicious stuff.

Then, let it sit for a few days. That will soften it up to be flushed out.

Concentrated muriatic acid will descale your tank in seconds, and then digest your engine.

Muriatic acid is used on cement decks and swimming pools. Here's an article on its safe use:

https://www.bobvila.com/articles/muriatic-acid/

Good luck with it.

Thank you, awesome.
Yes tank is plastic and has no maintenance openings or hatches. Scale is around 3-4mm thick that I found on the valves and pipes, assume its the same in the tank.
I can use swimming pool acid which is muratic acid due to the article you linked. Tons of swimming pools here,so should be easy to get.

[Rumrace]

Good old CLR and pressure washer. Add walnut shells to break up chunks. Flush with hydrogen peroxide diluted then water. Or buy a new tank and hoses.

[CaptainRivet]

Originally Posted by Rumrace

Good old CLR and pressure washer. Add walnut shells to break up chunks. Flush with hydrogen peroxide diluted then water. Or buy a new tank and hoses.

What is CLR?
Definitely not putting any walnut shells into the tank, you will never get all out of them and they will clog the pump and pipes without a chance to get rid of them…
Happened to me when I walnut blasted a engine block of a car and didn’t get all off them out of the engine and got flushed into the tank. Needed new pipes and tank because of this.
Swimming pool acid sounds a much better plan this desolves also big chunks of scale.

One tank I can pressure wash through the filling whole, the other is filled by first tank or watermaker.
Hoses are new from high pressure pump on and now also between tanks. New tanks out of question, then they stay like they are…it’s just a white crust inside on the walls and a bit on the bottom…just do it because all is off now and good access due to some repairs.

[CaptainRivet]

Originally Posted by tkeithlu

Sailorboy speaks with wisdom.

Is the tank plastic? The admiral/consulting chemist is hesitating to make a recommendation if it's aluminum. Stand by...

Here: Largely fill the tank with water and then add muriatic acid to about a 1:10,000 concentration, looking for a pH of about 4. That emulates vinegar. Do that in steps - don't pour the concentrated acid directly into the tank. Always pour acid into water in your mixing container. Be very careful - it's pretty vicious stuff.

Then, let it sit for a few days. That will soften it up to be flushed out.

Concentrated muriatic acid will descale your tank in seconds, and then digest your engine.

Muriatic acid is used on cement decks and swimming pools. Here's an article on its safe use:

https://www.bobvila.com/articles/muriatic-acid/

Good luck with it.

I tried swimming pool mutating acid and it failed. First mixed it due to instructions 6l on 50m3 or 5000l means 1l for 833l or 0,5l per tank…well I put even the whole 2l in one 300l tank and not much happened…

So I will use agua forte 5l with 50l water to get the bottom cleaned and then Yachticon Tank Supercleaner.
Replaced all hoses and marvelon valves (cleaned old and keep as backup)

[bil56]

install inspection hatches in the tanks!
you won't regret it ...

[CaptainRivet]

Originally Posted by bil56

install inspection hatches in the tanks!
you won't regret it ...

And this helps how to descale the tanks besides making a lot mess and work?
They are absolutely fine, just a thick layer of scale, nothing else...

[sailorboy1]

Originally Posted by CaptainRivet

I tried swimming pool mutating acid and it failed. First mixed it due to instructions 6l on 50m3 or 5000l means 1l for 833l or 0,5l per tank…well I put even the whole 2l in one 300l tank and not much happened…

So I will use agua forte 5l with 50l water to get the bottom cleaned and then Yachticon Tank Supercleaner.
Replaced all hoses and marvelon valves (cleaned old and keep as backup)

Well muriatic acid most definitely will dissolve calcium hardness type scale if used in a strong enough concentration and allowed enough time.

But there are other descales:

https://www.trac-online.com/products/descalers/psr