okay so I woke up this morning and 5 of my fish where dead. I need to know more about PH lvls. I think that is what killed them. My PH and Akilinity is very high in the water where I live...it comes out of the sink that way. I havn't had any problems with my tank untill I added the platties that I got. I started out with some danios and I have had them for about a month now and they have been doing fine. I've seem them playing in the tank and everything. 2 weeks ago I started seeing brown algea on my substrate...and even though I ran through it with my fingers it kept coming back. Then it started growing on the glass....I bought some Juli cory cats to mix the substrate around and that really seemed to help. The algea didn't go away compltly though so I looked up what causes it and read it was improper lighting or not enough oxygen. I then pruchased some plattys just to add some color to my tank temporarly. Also found a smallish pleco in the addoption tank where I work(petco). I've only had them for about 4 days...I noticed the first day they seemed fine. But then I started seeing them settling at the bottom of the tank in the corners together (like you would think of seeing egg layers in a nest) I have never seen platys do this. I also noticed they didn't seem to interested in food. I have tested my water every day since I have got them and my nitrate lvls are fine. I started getting kinda worried about them. I added a airstone to the tank 2 days ago....all the fish seemed to love the air stone...swimming up to it all the time. Yesterday I noticed I had lost 1 platy and 1 cory cat. This morning I found 3 more plattes and one of the danios. I did try to use some of the proper PH I got from work to lower the ph thinking maybe that was distressing them. Now I am not so sure...Please advise! What I really can't figure out is why the baby guppies I found in the adoption tank at work are not showing any distress...they are in my bio orb cause they are so small but they are just fine. I dont like seeing my fishies die....I want to see them all happy and this is the first time I have ever had trouble like this. Please help