Yeah look... about that, I can vocalise like an A*s at times so sorry for any offence caused. i am familiar with the " just one more fish" line and as you will see and hear from most people on here it soon becomes "go on, just one more tank" lol. 500 gallons? Jeez, you either have too much room or too much money
I plan to re-locate to australia at some stage and eventually have something of a similar size there. back you advice though- Once you are happy with your params and that your test kit works fine then dont obsess too much with that. I am gonna sound like a broken record but I really don't think your powder blue will survive where your naso didn't, in my experience they are actually quite a hard tang to get it right with and often dont do too well. maybe see if you can re - home the tangs until you are completely setup with your 500g and then SLOWLY re introduce over a period of a few months and only when you are happy that things are steady.
Anyway, good luck and please post pics of your 500g when you get it - it will make an excellent thread subject on here. Once again - sorry for beating my chest earlier!