How many liters of aqua soil in a mr. Aqua 17 gallon? Would a 9L bag do it ?
It all depends on your desired substrate depth. The 9l bags are surprisingly large when filling footprints. I think I used a bit more than one for my 20 longs, but I can't remember for sure. I had some decent depth to them as well because I made multiple tiers. So to get back to your original question, yes, you could use one bag to fill the footprint of the 17g.