Rust removal "washing machine" for vehicles.

[bigegg]

Try a cheap submersible pump

I was looking at those, but (if you mean the dirty water pumps) are 400-500W which seems massively overkill, as well as £££ to run non-stop for a week.

I also have a pond (fountain) pump on order - 15W - with a 3m head and is supposed to have "up to 1m" of fountain.

 

[Kayos]

I was looking at those, but (if you mean the dirty water pumps) are 400-500W which seems massively overkill, as well as £££ to run non-stop for a week.

I also have a pond (fountain) pump on order - 15W - with a 3m head and is supposed to have "up to 1m" of fountain.

Perfect to run from a solar panel and small battery?

 

[bigegg]

Perfect to run from a solar panel and small battery?

That's my plan, since I'm already set up for a solar powered hydroponics pond.
*If* it delivers enough fluid over a large enough area.
And my home made stuff isn't "evapobrakelines"

 

[Robotstar5]

You could re-purpose a Waxoyl sprayer?