Thanks for the prompt reply Simon. I know I probably have some nitrates, but the tank is currently filled to the brim with plants! I have a full mixed carpet and plants all along everywhere else, so I think I'm covered for the nitrates. Honestly the most likely problem is the lighting, and I've been wanting to get a light timer for this tank but haven't got around to it. My other tank has one and it works well. Chances are though if Australia follows suit to America and Italy with coronavirus prevention plans, I'll be staying home all day anyway and will be able to have lower light levels quite easily. So this is the permanent prevention fix I have in mind (self regulation while we are told to self-isolate, and a light timer afterwards if the shops haven't sold out of those as well!) and I will employ these as methods to avoid an algae take-over again. In the meantime though, I need to get rid the BBA and greenspot I have everywhere (and probably the hair algae... ?), so I'm looking for a way to handle algae through the whole tank. I'm moving my tts into my other tank so it doesn't need to be invert-friendly, but I have expensive and sensitive apisto fry in there as well (more photos coming soon!) so do need to be careful of that.
Cheers