[Fender]

So a few months ago I decided to upgrade my aquarium from 10 gallons to 36. I had 7 tiger barbs for a little over a year in the 10 gallon tank, with no deaths, while knowing nothing about cycling, ammonia, etc.

Now, with the 36 gallon tank, I'm having all kinds of problems (problems I may have had before but just wasn't aware of since nothing had died).

First of all, I know now that I made a huge mistake by putting a total of 13 fish in the tank from the beginning. Now, 4 months later, I'm down to 7 again (3 tiger barbs, 3 silver dollars, 1 gold gourami). After a few deaths, I bought a testing kit and found my pH level to be less than or equal to 6.0, and my ammonia count greater than or equal to 8ppm. It's now obvious to me what killed the fish.

So I guess my question is, what's the best course of action now? I tried an 80% water change, but even that only barely helped. I stopped feeding the fish for a while, and now when I do, it's only a few flakes once per day.

I've been thinking maybe I don't have enough oxygen in the tank. The gourami swims to the surface quite often and gasps for air. The air pump I'm using is from my 10 gallon tank. I ordered a new more powerful one, and it should be here in a day or two.

Another problem I'm having is a sort of growth I've never seen. It's an orangish-brown growth on the glass and turns the rocks and fake plants nearly black. I've read that algae tends to not grow until a tank has cycled.

Here's my current setup:
36 gallon tank
Tetra power filter 40
Proquatics 200 watt heater (kept at 78 degrees)


Thanks in advance,

--Brian