Why are you worried about the Nitrates? Nitrates are not very toxic to fish unless they are in high amounts. You can safely go to 40 ppm without any trouble. stress to fish cause aliments such as ich, weakened immune systems). Hardness of water is not a problem with goldfish. Mine are in very hard water and have never had any problems. Other fish I have that are in hard water are Balla Shark, Gouramis, Long Finned Black Tetras, and Koi. Also do not treat the ich with chemicals first try the three teaspoons per gallon of salt 3%. Every twelve hours add a teaspoon per gallon until you reach the three per gallon. So it will take you 36 hours to get to the 3%. Salt you can use is the aquarium salt or the canning salt from Walmart. Only pure salt no iodine can be used and no fillers. Only two I will use is aquarium or canning salt. Canning salt helps lower the price. Then everytime you do a water change you will need to add back the salt you remove. Only the salt you remove (add no more no less). Keep your fish in this 21 days. The things you really need to worry about are ammmonia and Nitirites, for these can kill your fish. The pet store can give you free water tests. Read about cycling a tank and proceed from there, for I believe your tank has not cycled with all these water chages and messing with the tank. I use straight out of the tap water to change my tank and to this I add Aqua Plus water condition. I put the water into 5 gallon Jugs and age it then I use it. I never adjust my PH and never test. When you start to adjust for this and adjust for that that is when the problems can start. Go talk to your local fish store and see how they keep their systems up and how your local water is. I keep up small water changes so there is no need too. I have never had any problem with Nitrates or PH. The small water changes every week keep my system clean and pure. Last time I had ich was years ago introduction of new long finned black tetras, and I just added the salt for 21 days and it has never returned. Hope this helps, for it can be very confusing out there as one person says this and one person says that. I am not a person to use too many chemicals, so salt is my first choice. I believe the fish are stronger and less apt to be sick in the long run. Look up Nitrites, Nitrates, Ich and salt, and cycling a fish tank over the internet and you will learn a lot.

I can't add much more to what Sandy said except to confirm, that my ph stays high (even with wood in tank) (due to muncipal adding lime I think after calling)even though it comes out of tap at 5. Only have to slowing acclimate fish and all are fine. Gouramis, bettas, asian glass cats, various cory cats, and priscella tetras (I read they can handle harder higher ph) I do small twice weekly water changes to make sure it doesn't go above 7.6.

Cloudy means still cycling... maybe too much fish all at once even though you used older bacteria from early tank. ie start with goldfish.

I would think having moved him to let him have larger size, you added more creatures which negated this somewhat. He is a fat round goldfish one inch per gallon needs to be upped. I raised golf fish outdoors in (baby pool) pond and each had about 4 - 6 gallons each. Indoors even more gallons per fish.

What are the other fish.. goldfish like cooler water (person at pet store told me crab eaters as well, and if fish smaller then crab crab eats fish) did you put angel in with goldfish...

For best interest of both tropical should be in tropical setting, and goldfish with same or those of minnow cooler water fish. Angelfsh needs much higher temp then goldfish...but maybe I misread?

I like Sandy, as well mostly now use salt (some exceptions parasites per Gourami for instance) esp with ick higher temp and salt and bottom cleaning daily... (Dr. Innes great old book but steller advice, just reverted to what I used as a younster when I raised fish)

Would only add mix salt with water ie don't add directly to water. slowly add over time to build level then reduce in reverse to level of normal.

so, cycle properly. Treat fish for ick with salt and temperature,

Take out warm water fish and treat seperately, and keep seperate MHO... best for both. goldfish are so much more 'dirty' as well...do much better at cooler temps whereas this will stress others.. (if they are tropical, you don't say)

Add a companion goldfish or two to larger tank for buddy and thats it, but add after it's cycled with him then one at a time, to let bacteria build up to handle additional waste.

I use bio stuff to speed this up... (works as I see them crawling) My water due to NYC horrible water, is aged and pre pre filtered (or brown!)