QTOFFER's advice about doing water changes is excellent. Keep doing small water changes until you get all the food from the vacation block out. This just feeds the algae.
Also, the pH seems a bit high at 8.0. Ammonia can become more toxic at higher pH levels. Doing water changes with RO
water is good and will get the pH down too. But don't have all RO
water in your tank. There are some beneficial minerals in tap water that fish need. (freshwater fish, anyway!) When you've replaced half the water in the tank with RO
water, then do your water changes using a 50-50 mix of tap and RO
water. My tap pH is 8 or 8.2, and I use a 50-50 mix of tap and RO
bacteria really isn't that hard to fix. I got a horrible outbreak when I used my under-cabinet halogen lights for the tank lighting. The two-gallon Eclipse has a biowheel filter but no light, correct? I taped newspaper (2-sheet thickness) around my betta tanks (I have two 5.5 gallon tanks) so no light would get through. Lay some newspaper on the top too, to block the light from getting in the top. I taped a narrow strip of newspaper to the top of the tank, but didn't tape it to the bottom, so I had a piece of newspaper to lift up and check on the betta. Your betta will be fine in the dark. If you feed him during this dark period, feed him half of his usual amount, or feed every other day. It wouldn't hurt him to go for about 3-4 days without food also. Is he eating now?
I also put some erythromycin in the tanks. I used about 100 mg
. per 5 gallons. I took the sponge filters out of the tanks, and put them in those freezer zip-lock bags, with some tank water. I then put them in the refrigerator. The frig is dark inside too, so the cyano
on the sponge will die in the dark. You could put your bio-wheel in the frig too. In such a small tank, though, I would see how the dark treatment does first, then use erythomycin for 5 days (about 50mg for 2 gallons) if the cyano
I would keep the tank dark for 5 days while continuing your water changes. Hopefully that will turn things around for you, and the betta will perk up!