So I have a 29 gallon tank. In January I got a betta fish (BlueBlue) and in February I got a clown pleco. I have been cleaning the tank by doing water changes every 2 weeks. I use stress coat from API and whenever I need to,I use the ph up, never had a problem. So one day I read that plecos need driftwood, so I got two pieces of driftwood in the tank. After that I started getting brown algae, and no matter how many water changes I did... still coming back.. and fast. Well, my dumb self decided that I was going to replace the gravel and do a complete cleaning of the tank. Went to petsmart and bought new gravel (colored one) pink, blue, purple and green.Also, I got something call “ceramic rings? Fluval brand.. first time using it. Well, this morning I woke up with my betta fish dead in the bottom of the tank and my pleco has something white covering its eyes, he is not eating and doesn’t seem to be acting normal and his belly looks kind of big. Also, not sure if its the dye of the gravel, but it looks like it has some red on its fins? I'm sorry for the long post , but I'm very upset and not sure what else to do. I feel so guilty. Including pics.