Invest in a refractometer. The swing arm hydrometers are rarely accurate or consistent. A calibrated refractometer is a friend.
Get an RODI
system and make your own water. It's cheaper in the long run than buying water. Any water you buy MUST be tested before use to make sure it meets your desired parameters.
If you have a QT tank, USE IT for all new livestock acquisitions. Right now you should have any and all fish in the QT and treat them with hyposalinity
for 6 weeks, while the main tank remains free of fish for 6 weeks. This will make it highly unlikely that you will get another Ich infestation.
Here's my 10 rules for a successful aquarium:
Rule # 1. Nothing Good ever happens Fast in a salt water aquarium
Rule # 2. Don't add anything (supplements/chemicals/minerals)you don't test for first.
Rule # 3. PWC
(Partial Water Changes) are your friend, and cure many ills.
Rule # 4. QT EVERYTHING before adding it to your tank (mandarins excepted, corals should be dipped)
Rule # 5. Use only RO
water (either buy it or make it)
Rule # 6. All animal species live longer on a 30% reduced caloric intake. Only feed every other day at most (fish species dependent)
Rule # 7. Hyposalinity is the best, safest, and most effective treatment for marine Ich (IMHO
Rule # 8. A Refractometer is a MUST HAVE, not a luxury.
Rule # 9. Anemones will never live anywhere near their normal (approx 30 years) lifespan in a home aquarium. Leave them in the ocean.
Rule # 10. The tank size recommendations for fish are there for a reason - HEED THEM!
I have been asked to add
RULE 0 - Don't believe the LFS