hospital tank

[miniman78]

PLEASE HELP, I lost a pearlscale butterfly 8 days ago which i thought was because my yellow tang was bullying him and stressing him out. I have now have white spots on most fish for about 7 days. no cloudy eye no rubbing or scratching and my regal blue is completely spot free?? is this ich? also on my bannerfish angel a tiny chunk is missing from his tail. i have dipped all fish 3 times.
I have a tank ready to be set up for qt but also need help with this. how long does the sponge filter need seeded for? should i use DT water or fresh saltwater?
help appreciated
PH 7.8 - 8
ammonia - 0
nitrite -0
nitrate - 15-20 (doesnt seem to lower on water changes)
salinity- 1020
temp 28deg c

I

[leebca]

WELCOME TO REEFLAND!

Sorry your problems prompted your first post. The first thing you want to do is make a good diagnosis.

What you need to do is all spelled out in this one post, which has links to other posts. You can get the whole picture by starting with reading and following this link: Curing Fish of Marine Ich

You have a lot of reading to do. If you have questions, please ask. But first read through all the information provided. Much more info in those links than I can write out here.

I'll answer your immediate questions, but the details are given in that link and the links within that post:
1. It could be Marine Ich. You need to diagnose it yourself. Not all fish will display the parasite at the same time -- some just don't. Learn about the parasite. Get pictures on the Internet to compare to what you see.

2. Dips have no affect to stop Marine Ich, if that is what it is.

3. The chunk missing implies either poor water quality, an injury, or tank mate problems.

4. A sponge filter -- biological filter -- can take up to 6 weeks to start. You will be making many water changes OR you will make a few water changes and use chemical filters until the sponge filter starts working.

5. DT water can be used to start the quarantine - hospital tank. After the initial setup, only freshly prepared water can be used.

6. Even though a fish tank, you need to control Alkalinity, Calcium, and Magnesium AND they have to be kept in balance (not just in the right range). I am assuming because you didn't report these numbers, you aren't watching them.

Good luck!