we've been gone on vacation for over two weeks and before we left we did a partial water change for our 10 gallon tank. we noticed a little hair algae growing so we got a few ottos before we left. i just checked the levels and everything and noticed the plants are starting to die.. there is that dark hairy algae on all the plants.. and the ammonia levels are sky high. the pH is low too but the nitrates and nitrites are just fine. the tank has been set up for a while now so i was wondering if there was a link between the problems or not. any opinions???