Ich and start up tank

Question
Hi Matt,
I know for sure that I made a mistake when I purchased these White Mickey Platties from the shop because thew rest of the fish didn't look good but I picked out the ones I thought still looked ok but now one has died suddenly with no signs and 2 that are left - one still shys away from food and both now have ich. They had this before and I thought I cured it in 3 days with meds. but now its back again. I have quite a few fish in the tank but they don't seem to be affected and look healthy as they did before these white ones came (about almost 3 weeks now#. I do weekly water change.
My questions are : -
1. I have set up a new tank to give more space. Can I put a few healthy looking ones from the old tank as start up fish #4 white clouds)?
2. I have been suggested 2 millions ways to start up and am totally confused. Safe way, no fish way, natural way with or without fish then I was given products including one which is the Bio-Digest. I was told that I can put fish in, add the product and put one more 2 weeks later to maintain and should safely avoid dangers of cycling the new tank. What I don't understand is if the product eliminates nitrites and clean fish waste then will that not stop the good bacteria growing ? Also won't that start the cycle all over again if I stop using it later ?
I hope that you can help me since I cannot seem to get one straight answer from anyone here.
Thanks.
Michael

Answer
Hi Michael,
There is a lot of issues with cycling a tank because many people want it to be done and get it over with.  The products that the stores sell that say, "add this and your tank will me immediately cycled and safe for fish" is not true.  To cycle a tank, you are trying to grow 2 sets of bacteria.  The first set breaks down ammonia-to-nitrite and then after that another set kicks in which further breaks down nitrite-to-nitrate.  However there is no 3rd set of bacteria that breaks down nitrate, so the only way to remove this is by water changes.  Which is why 15%-20% water changes are recommended weekly.

There are 2 ways to cycle.  With fish and without fish.  There is no other way.  To cycle a tank, ammonia must be introduced or else the 1st set of bacteria will never be able to grow.  When people cycle with fish, they use the fish's waste as a source of ammonia.  To cycle without fish, they need different source of ammonia, so why not use straight ammonia itself?  Pure ammonia that do not have any additives such as scented ammonia are used to cycle tanks.  It is a lot faster and more efficient.  BUT, if you do not understand the nitrogen cycle, it will be confusing to do the fishless cycle.

If you plan to cycle with fish, you add the fish you want and do water changes every 2 to 3 days because you dont want the ammonia and nitrite to get too high.  You resume it to weekly after the tank is cycled.

To cycle fishless, you need ammonia in a bottle and a liquid test kit which are sold at fish stores.  You add ammonia to reach a concentration of 6ppm and you maintain it there every day until you see readings of nitrite.  From there you continue to add ammonia until you see readings of nitrate.  Once you see readings of nitrate, it means both sets have been grown.  Or else nitrate would never be able to appear.  At the end of a fishless cycle, you do a 90% water change at the end, add new water and you are done.

To answer your questions
1. Yes you can add the healthy fish, this will cycling with fish.  Be sure to do water changes every 2-3 days as stated before to keep nitrogen levels low until the tank is cycled.
2. There is no product that eliminates ammonia nitrite nor nitrate.  Think of it this way, if you add food which turns into fish waste, it must be removed somehow.  You cant "remove" it by adding chemicals.  You remove it by doing water changes.  What goes in the tank, must come out.

Let me know if it is confusing or if you want me to clarify something else for you.
-Matt-