Ok, so here's the deal. in my 20g tank, some of the fish that i have in it are tetras ( 3 neons, 1 Rummynose, 1Cardinal ) and yesterday i noticed the 3 neon tetras were very black. Today
they look even worse, even darker, one of the tetras tails has orange rather than red. They also have a bit of trouble swimming. 3 Days ago, i treated the tank for ich, but now it's gone.
Yesterday i did my water change, added the Stresscoat, Aquasafe etc. Anyway, can you people please help? i'm thinking it's the chemicals

No one?

tetras do require slightly diffrent ph from other fish due to were they come from that could be stressing them making them go a diffrent colour

any chemical that stabilizes ph is a huge no-no

if you continue to add ph buffers your ph will continuously fluctuate

first, what is the liquid test reading on the ph? Second, can the fish you have handle the ph? And third, you can always either add real wood or shells to lower or higher the ph naturally, depending on the reading

so we need a reading on the ph?

yea when you buy fish from the store unless youre going counties or states away they are raised in the same ph water as your tap. Therefore already acclim8d...n stuff. I say just buy some cichlids and let em eatem. You'll thank me l8r promise.

ammonia and nitrite is fine

ph at 7.2 is fine

nitrate - is it a liquid test kit, and if so, did you shake the bottle for a good 30 seconds, then shake the glass tube for a good minute? Also test kits do age, after a good year, one should replace the test kits

nitrate can range anywhere from 0 to 40 and fish are fine - above 40 ppm, the toxicity will cause stress

as for an ich breakout - if you raise the temperature slowly in the tank it will slow down the ich's biological process so it will not spread as quickly; after this, depending on the fish, add aquarium salt which will also dismantle the ich chemical processes and help the fish ward off any of the pests - leave the temp at around 85-90 for about 2 weeks; lower the water surface about 2 inches so the water can splash down onto the water surface from the filters (I assume you have hang on back filtration system) which will help with the depleted oxygen supply (higher temperatures mean less oxygen in the tank)...slowly lower the temperature to your normal level, usually around 76-78, and the ich outbreak will be solved

I'm about to blow your mind on this one toxic, but I have 4 kuhli loaches, and the ph that comes out of my tap is 8.1 ph, yet the loaches as well as the other living inhabitants are fine; why? because it is stable - fish can handle a stable higher ph than a fluctuating one, understand?

an established tank is a stable one, very few spikes in any chemical levels (if at all)...in the tank I have, I have no filtration system, yet the chemical tests are stable, thereby, the fish are stable or have less stress, and that makes for a healthy tank, understand?

let us know how it goes

What people are telling you is to not use the proper ph EVER. A ph of 7.2 is not high enough to be concerned about. As for the "aqua safe", i'm not sure what that is. If it is a water conditioner/dechlorinator, then it needs to be used with every water change.

Aquasafe makes 2 products if I remember correctly. A product to speed up the cycle (the fake bacteria stuff) and a dechlorinator. Products that speed up the cycle rarely work, so if that's what you are using then theirs no need to do so. And stresscoat (which you mentioned using in an earlier post) does the same job as aquasafe's dechlorinator, so if that is the aquasafe product you own there is no need to use it if you are already using stresscoat.

What yasher was trying to explain to you concerning lowering the water level was an alternative method to cure ich. If your ich is already gone thanks to a treatment you bought in the pet store then their is no need to lower your water level. Just consider yourself the luckiest fish owner alive for treating with a store bought cure and your loach living through the ordeal.

The fact that your nitrAte is 0 and that you cant get a good reading on your nitrIte concerns me a little. If I were in your position, having a possibly faulty test kit and sick fish, I would bring a water sample to the pet store and ask them to test the levels for me. They usually do that for you at no cost.