Might have spider mite on tomatoes

[Cheesipuff]

two of my four tomato plants in the greenhouse have tiny white marks on some lower leaves. Seems it could be aphids or spider mite.
Plants are only 18 inches tall.
Apparently I can spray with a soap wash - has anyone done this?
I would think bar soap would make a soap wash is this correct?

Have you got a picture?

The air in the greenhouse is too dry then. Red spider mites love those conditions, but the tiny white marks could also be whitefly, or damage on the leaves caused by thrips.

Use a proprietary organic fruit & veg insecticide spray, don't bother messing around with soap yourself. Spray both sides of the leaves, and once treated, increase fresh air movement through the greenhouse.

Yes, that makes sense - it has been sunny all day for days until now.
They are tiny holes with a white edge. I'm not sure it's spide mite couldn't see any bugs on the backs of leaves.
Will get some insecticide.