1) I saw units at c328. Call them to ask.
2) Perhaps 2 months? They are liquids so you're essentially buying diluted chemicals we use. You can try them first, to understand completely what plants need. After that, it'll be easier for you to understand the chemicals we use often, or you can try other commercial ferts.
3) Yes it's mainly just colour difference. Yes, you can't do that for Aquasoil. It's not good for frequent rescapes. Otherwise it's a very good substrate to use. What I do when I change Aquasoil is to dig out the whole thing and use it for my potted plants at home and replace the tank with fresh Aquasoil.
4) Dennerle has dark coloured Quartz gravel but I'm not sure about the colour. Do a search will help. Ferka only has base fert (called Aquabase).
5) Leave them in a pail of water. It'll be better to get all the plants thus, Colourful Aquarium should be able to supply you with like 100% of the plants you want.
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