The ammonia and nitrIte are really all that's important right now. I wouldn't let any pH, kH or GH levels cross your mind. The focus should be in getting the toxins low and keeping them there until the tank is stable. I personally advise doing enough pwc's to keep the ammonia and no2 at or under .25 at all times. This may take several back to back changes. Let your test kit dictate how much water to change and how often to do it. Don't let the clock be your guide...just your test kit.
A few tools which can help...first, if you don't already have one, get yourself a quality liquid test kit like an API Master kit. It'll be vital to have an accurate reading every day.
Second, continue to use the Seachem Prime at 2-3x the normal dosage for now which can be a huge help. It dechlorinates the water, but also temporarily detoxifies the ammonia and nitrIte for 24-36 hours to buy your fish time between pwc's. It only neutralizes to a certain level, so don't use it as a substitute for fresh water to keep toxins as low as possible.
Third, aquarium salt can be helpful during the nitrIte spike phase. It will help reduce the uptake of the nitrIte and help your fish make it through.
First and foremost make sure you do water changes ASAP. We've got to get the no2 down immediately. It may take several back to back changes, but shoot for .25. Having nitrItes at 5ppm is absolutely devastating to your fish, and we've got to get that level down immediately.
Just keep up the testing, perform water changes as necessary to keep toxins at or below .25, try to pick up the other tools at the lfs when you can...and we can get your fish through this. It's just going to take some diligence and commitment
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