Screwfix descaler instead of Rydlyme?

[ridgy]

My engine needs has some deposits for sure, if I take the anodes out and put my finger in I can feel it, quite bad in one of the anode holes. Yesterday I ran Rydlyme round for a couple of hours and I have to say it didn't seem to do much.
Conversely past week I cleaned my prop with this stuff and it seemed very efficient:
https://www.screwfix.com/p/scrubb-calcium-limescale-rust-remover-1ltr/879ve

It has the same instructions to dilute 50/50 with water. Tempted to repeat it with this, wondered if there was a reason for Rydlyme to be the usual stuff mentioned.

 

[Alex_Blackwood]

My engine needs has some deposits for sure, if I take the anodes out and put my finger in I can feel it, quite bad in one of the anode holes. Yesterday I ran Rydlyme round for a couple of hours and I have to say it didn't seem to do much.
Conversely past week I cleaned my prop with this stuff and it seemed very efficient:
https://www.screwfix.com/p/scrubb-calcium-limescale-rust-remover-1ltr/879ve

It has the same instructions to dilute 50/50 with water. Tempted to repeat it with this, wondered if there was a reason for Rydlyme to be the usual stuff mentioned.

It doesn't seem to mention anywhere if it is suitable for alluminium /alloys.

 

[Boater Sam]

It is basically Phosphoric acid with a fragrance added. An acidic rust proofer.
There are better chemicals for dissolving lime scale. You need an acid to dissolve lime scale.
You have to be sure that there are no metals in the system that will react with the descaler. I would suggest neat white vinegar as a first call.

 

[thinwater]

The Screw Fix Scrubb SDS says it is lactic acid. A similar US products (CLR) has been tested and found to offer the best combination of descaling and limited corrosion of aluminum. This is probably as close to aluminum-safe as you will get, but Google for UK experiences or better, testing. Rydylime is based on hydrochloric acid, inhibited to reduce corrosion of steel.

Hydrochloric and phosphoric acid are commonly used with steel but are dangerous for aluminum. Citric acid is another good aluminum choice. [Are there any aluminum parts? Marine engines often avoid that, except for outboards and drives.]

SDS for Scrubb. Lactic acid.
httpsRydylime SDS. HCl.

PS testing of lactic acid cleaner on aluminum

I would not work towards perfect. It probably removed enough and more might risk corrosion.

 

[ridgy]

It's a yanmar 2gm, can't imagine there is much aluminium in the waterways?

 

[PaulRainbow]

The Screw Fix Scrubb SDS says it is lactic acid.

You are using the wrong SDS, use the one at the bottom of the Screwfix details: MySDS

Which actually says "
Hazardous substances: phosphoric acid, Isotridecanol, ethoxylated"

A similar US products (CLR) has been tested and found to offer the best combination of descaling and limited corrosion of aluminum. This is probably as close to aluminum-safe as you will get, but Google for UK experiences or better, testing. Rydylime is based on hydrochloric acid, inhibited to reduce corrosion of steel.

In which case

Hydrochloric and phosphoric acid are commonly used with steel but are dangerous for aluminum.Citric acid is another good aluminum choice. [Are there any aluminum parts? Marine engines often avoid that, except for outboards and drives.]

SDS for Scrubb. Lactic acid.
httpsRydylime SDS. HCl.

PS testing of lactic acid cleaner on aluminum

I would not work towards perfect. It probably removed enough and more might risk corrosion.

 

[thinwater]

Good catch. Scrubb also sells a "lime scale remover" that is lactic acid. One word in the title makes a difference. Interesting. Lactic acid is better at removing limescale without damamging metal, but as a corollary, it is not as good at removing rust. HCl probably bemoves rust and scale the fastest (concentration always matters), but at the cost of corroding or damaging most metals. Phosphoric removes rust well and leaves a conversion coating that inhibits rust (something like Parkerizing), but there is collateral damamge if it is there too long.

It is bad to leap to the conclusion, based solely on the SDS and published spec sheets, that these products are only the main acid plus fragrance. They also contain surfactants, corrosion inhibitors, and chelating agents. Some are listed on the SDS, but non-hazardous ingredients are not required to be and are commonly withheld as trade secret.

 

[ridgy]

I ran a bottle through for 20 mins or so, water turned brown and foamy so did something. Rinsed well and engine still runs. Still significant deposits but I'll do it again next year.