New tank set up?

Question
Hi,
I've been reading through some of your previous questions, I'm new to the tropical tank world and am unsure of what I'm doing.
I've tried to ask at local pet stores but I'm not quite sure where I'm at as I'm getting contradicting information.

I have a new Aqua one 850 tank, approximately 160 litre tank, it's been up and running for 5.5weeks. We have 9 neons, 8 guppies', 1 silver shark and 1 dwarf Garami. The water is sitting at 25 degree's and holding a pH of 7.3 which we keep dropping to 7. The nitrate is at 0, but ammonia level is at .25 daily and isn't reading at 0 even after a 50% water change. We've been changing 1/3 to 1/2 the tank water weekly.
Is this normal and should I be worried about these levels.
I'm new to this and happy to change water and know that a new tank setup is alot of work. Am i doing it right? Is there anything else I should know?
I'd love your help.
Kind regard's
Kelly

Answer
Hi Kelly;

There may be too much waste in the system too soon. Feed lightly for awhile until it stabilizes. Only feed what the fish will eat from all areas of the tank in less than 3 or 4 minutes once a day. Leftovers anywhere will elevate ammonia. The tank is still in the break-in period so it just isn't stable yet. You might take a look at your water conditioner too. Some water conditioners can cause a false-positive result on an ammonia test kit. If your water conditioner says it controls ammonia, try a different type of ammonia test kit. You need one that does not contain something called a "nessler reagent". The label will usually tell you. It is best to use a "salicylate" ammonia test kit instead. Salicylate kits will show the colors as yellow for "zero" ammonia to shades of green for elevated ammonia. Let me know if you have more questions about that.

There's quite a lot of fish in there to get it through the break-in period without having some trouble. There should only be one fish for every 40 liters (or ten gallons) until it is fully stabilized. Here is a link to my article on new tanks to help you know more about the first few weeks of your new aquarium and what's going on in there;

http://www.xanga.com/Expert_Fish_Help

You mentioned attempting to alter the pH. Don't trouble yourself with it. A pH value of 7.3 is great. It is very stressful to the fish and to the beneficial bacteria to try to change it. It causes fluctuations. What we are looking for is a stable pH, not a certain level. Besides, it's too much work. Make it easier on yourself and the fish and just let it be. ;-)

At Your Service;
Chris Robbins