Algae stain on wooden swing seat

Hi

I used to use Cuprinol to preserve exterior wood. Is there a preservative I can apply to the soft wood swing seat that will kill the algae or do I need to lightly sand the green algal stain off before treating?

I've found two products that should help:

Garden Furniture Cleaner | Ronseal

https://www.amazon.co.uk/Rustins-DA...&hvtargid=pla-2281435179258&gad_source=1&th=1

 

I use Patio Magic on my painted wooden garden furniture and fencing. The algae disappear usually with 24 hours. If necessary, after that time, I apply another coat of paint or preservative.

 

I cleaned an old seat up pretty well with a pressure washer, of course you really need to dry it out pretty thoroughly before using any preservative afterwards.

 

I think if you simply scrub the seat with hot water containing liquid bleach, you will remove green algae. Only scrub with the grain. Allow to dry thoroughly ( 7 days ?)
Not keen on using danish oil on a surface thats sat upon. Yacht varnish would be better, 2 coats, It has the advantage of being recoatable subsequently without stripping.
Otherwise exterior acryllic finish.

 

I used to use danish oil on my outdoor table but it wasn’t the best for use outside. I have switched to Screwfix no nonsense garden furniture oil and it has been much better. Still need to apply it once a year.

 

I've read Screwfix no longer sell it.

This looks good:

Barrettine Wood Protective Treatment 5L