Welcome.* I would recommend finding a local fish store if possible. Find out if they carry BioSpira and if they do, get some quick.* Also find out if they can take the pleco, as its going to get really huge and is a serious poop machine that won't help with the current problems at all.* Most pet/fish stores will also test your water for free. If you take it in, tell them you need it tested for ammonia, nitrites and nitrates and don't let them tell you "fine," "high," "low" or anything of the sort.* Tell them you need specific numbers. If you do buy your own test kit (highly recommended), get liquid kits with test tubes, not the ones with strips. The strips aren't nearly as accurate.
BTW, don't let them sell you anything to help with the cycling process besides BioSpira. Nothing else works. Not Cycle or any of the other products in bottles on shelves. Only BioSpira and it must be kept cold in the fridge until used.
