Soil going green

Hi,

I have a few pepper plants and a couple of chilli plants in pots on my conservatory window cill and the soil has started to go green on the top, also the same on two bonsai I'm trying to grow.
Quick google search says too much water but I'm worried about the bonsai as I read not to let them dry out at all so if I scale down the watering they might die, they are only just under two years old so still really small, what colour should the leaves be? and are they even leaves or are the branches?

 

I'd be thinking to scrape the green algae off carefully and then put a nice layer of grit/fine gravel over the surface.

 

Sorry for the delayed reply, I didn't get any email notification even though I have set it to notify me if I receive a comment.
Here's a pic of the Bonsai, the leaves or branches are nearly all brown now, is this normal?

Thanks

 

They did have green leaves not so long ago but the soil went a bit weird so I potted them into a bigger pot, too big then?
Yes grown from seed since April 2020
They are called Pinus

Thanks

 

I do have a moisture meter but how do I know how moist the soil should be?

What type of gravel should I use for the top of the soil?

Thanks

 

Can I just say that they should be bigger by now .
They are a hardy tree and would benefit from being in a sunny spot outside.
You need to let the surface of the compost become dry before watering.
Push a finger in the compost and if it's dry about an inch down water it, if not don't water.
This method also stirs up the top of the compost allowing in some air which will help prevent the green algae forming.
Unfortunately it doesn't look very well in the picture and I think you might lose it.

 

Just my thoughts but I hate using grit on the surface of posts for the one reason that you can't see the compost, so if it's wet or dry under the grit you don't really know.