Purchasing water

Question
I just talked with someone at the local aquarium store, and I wanted to get your take on my situation as well.

I have a 29-gallon tank. I kept it for three years with no major issues before I was sent overseas with the military. I had live plants and kept mostly livebearers and neon tetras. My brother-in-law kept my tank for me while I was gone, and made a lot of changes. Also, he got incredibly busy and wasn't able to maintain the tank all that well for the last few months before I returned.

The tank now has artificial plants, and the only fish remaining were one gourami and two different tetras. We moved the tank back to my place about two months ago, and I cleaned the tank up and got things running again. After a couple of weeks I added 6 zebra danios to help break the tank back in. After about two weeks, three of the danios and one of the tetras died, leaving me with three danios, a tetra, and the gourami.

The main thing I'm worried about is that the pH of my tap water is over 8.0, so lowering it for fish is obviously very difficult. My tank stays around 7.8 or so. I want to be able to add fish, but first I'd like to switch to live plants.

The folks at the store talked about using either Reverse-Osmosis or Deionized water for my water changes, as that would help with the pH.

What is your take on my situation, and what course of action would you recommend. I'm very patient and I'm not going rush off and buy 10 plants and 30 fish tomorrow.

Answer
Dear Trey,
Well, I'm glad you are a patient fishkeeper!
Sounds like you are going through a hard time with cycling your aquarium over again. It was likely ammonia that caused the loss of your danios and tetras. The best thing to do is insure to test your ammonia and nitrite levels daily and if they are ever above safe bounds, immediately do a 50% water change and re-test again to insure that the water change was sufficient enough.

It is well-known now that adjusting your pH is generally uneccesary for good fish health. pH is important for fish, but it's the real truth that fish are very adaptable creatures now that most have been bred in captivity for many years, and they have adjusted and now thrive in water chemistry that is less than ideal and what is recommended in books or what they would be found in back in nature.
Adjusting your pH can also do much more harm than good. Lowering a high pH is much harder than raising a low pH. This is because a consitantly high pH, naturally has a high alkalinity that buffers the pH to that constant level. So whenever chemicals are added to lower the pH, the alkalinity just absorbs it back up. So these pH lowering chemicals only work for a short while, and in no time the pH has jumped right back up again. This all results in a pH rollercoaster of ups and down and this is extremely stressful for all fish. I also have a high pH and hard water and know many other aquarists who have a  very high pH. But since their fish have adapted well, nearly all captive-bred and reasonably hardy fish will thrive and sometimes even spawn in a less than ideal water chemistry. Remember it's much more important to provide your fish with clean water with a stable chemistry than one that is constantly adjusted. And as long as you insure the water is clean with plenty of water changes and the temperature is correct, that is all most fish will ever need.

You can certainly use R/O water mixed with tap water to achieve a desired pH level. This can be a hassle though. But if you wish to do so, then that is perfectly fine. Just be sure to never use RO straight as it is almost devoid of all minerals that are important to the health of fish and therefore you should always mix it with some tap water. But remember that in general, adjusting your pH is almost entirely uneccesary.

Ask your local petshop what pH they keep their fish for sale at. Sometimes it is the same exact pH your own tap water is and so those fish would be acclimated to that water already. Just remember to always make any pH changes or any other water chemistry changes slowly.

Well, I really hope this helps!
Best wishes and Happy fishkeeping!
Karen~