Cory Catfish

Question
I have a small tank, one and a half gallons to be exact.  
Before buying fish I asked someone at the pet store what all do we need for the tank. This is why I purchased the Aqua Safe and thought that was all I needed.
At one time we had 3 guppies, a plant, and a Cory Catfish.  
The three guppies died at different times.  We changed the water weekly and filters biweekly.
I started to use  Distilled Water after loosing our fish. I thought that it would be safer.
Someone told me that the reason I lost my fish was that I needed to add the Easy Balance with Nitraban and Aquarium Salt to the water.
I tested the premixed water before changing it and the PH was (6.2) and Total Alkalinity was (0). I bought PH tablets at the store that were supposed to help this problem. It did not work.
I made up new water this time without the Easy Balance Nitraban and that the PH was (6.8) and the Total Alkalinity was(40.)(It only had the Aqua Safe and Aquarium Salt in it.) I also, mixed up The Easy Balance with Nitraban and added the Aquarium salt but the PH was still (6.2).
These are my questions:
1. Is the Easy Balance with Nitraban necessary?
2. Is using Distilled water good or bad for the fish?
3.  We want to get this Cory Catfish a friend and were going to buy another one.  However, we don't want to until we get this water problem completely solved. Any suggestions?
4. I feed our fish some Flakes.(Tetra Color Tropical Granules)  He does not seem to like the Bloodworms(Tetra, freeze dried food).  He did when the Guppies were in the tank. What do you recommend we feed the Cory? 5. And should we get another Cory Catfish so he isn't alone?
Thank you so much for your time and input.
Debbie


Answer
Hi Debbie,
I'll try to make this as simple as I can.

Don't bother with easy balance, nitraban, pH adjusters or aquarium salt. Only use water conditioner (aquasafe is fine)

*Those things make the water quality unstable and its just too many chemicals that prove stressful to fish. They are completely unnecessary.

Just use normal tap water and always remember to add water conditioner to it.

*Distilled water lacks minerals the fish need to be healthy long-term.

Being that your aquarium is small, it doesn't take long for pollution to build up and being that the tank hasn't been setup for long, there aren't yet enough "good bacteria" developed to help remove the toxic waste the fish produce--these bacteria need several weeks to establish and during that time ammonia from the fish can build up to very toxic levels quickly. 50% water changes are needed to battle this problem until the bacteria establish enough to keep it non-existent.

*Ammonia, nitrites and nitrates are the most important things to test for.*

*Feed your cory some sinking tablets made for catfish. They usually enjoy these much better. And try small amounts of frozen fish foods like brine shrimp or worms.

To be honest, it is pushing it with keeping two cories in 1 and a half gallons. Unless you are very consistent with 30-50% water changes three times a week you could have pollution trouble a lot.

It would be much better to upgrade to an inexpensive 10gal tank with hang on the back power filter and heater. It would make a much healthier environment for your fish.

I hope this helps and have a good weekend!
Karen~