Stressed fish

Question
Hi Dave, I have a 47 gal. tall aquarium with 50 lbs. of live rock and 40 lbs. of live sand. After cycling the tank with the live rock I dosed the tank with a product called Instant Ocean nitrate reducer and started putting in 5 ml. per day of a product called purple up.(calcium and iodine). After 2 weeks I put in 2 tank bred ocelleris clowns and continued with the purple up. 3 days later one of them was dead while the other looked perfect. I thought I just got a bad fish so 2 weeks later I added a cleaning crew (30 snails, 30 crabs and 3 shrimp). That was about the time I was having a major outbreak of brown algae. two days after that I added another clown and a yellow tail damsel. Everyone seemed to be getting along great and eating great for 5 days. On day 6 when I turned on the light in the morning I could see something was wrong (no eating and all had some white film on them. The next day both the clowns were dead and the damsel is swirling the rim. All the parameters that I know to test for seem perfect(no ammonia or nitrites, nitrates and phosphates are very low, ph, alkalinity and salinity are all good). Even though I had continued to use the purple up, as far as I can tell the calcium is less than 300 ppm. However now the rocks are covered in some areas with white (calcium?) where there was some spots of purple algae started. Could my problem be too much calcium? If I don't add anything will there be enough calcium from the live rock and sand? What can I do going forward to prepare the tank for new fish? So far everyone in the cleaning crew looks OK.  Sorry for the long question, trying give you as much info as possible. Thought I had this all figured out. Thanks for any help you can give.  Mike

Answer
Hi Mike,

Sorry to hear of your troubles...

For now, I would stop dosing the aquarium with the CaribSea Purple Up. This will give the aquarium a chance to balance itself. The live sand and live rock will provide plenty enough calcium for your remaining clean-up crew pertaining of snails, and crabs, and for your purple coralline algae. If you plan on turning your aquarium into a full reef tank, then you would want to be more precise with your calcium calculations and dosing.

From just doing normal water changes, (while using a good synthetic salt mix), will provide sufficient calcium levels for your FOWLR (Fish Only with Live Rock).

Also if you haven't installed a good protein skimmer yet, I would strongly advise to do so. A protein skimmer will help maintain water parameters, by keeping the water cleaner, thus the water will be more stable from keeping the DOC (Dissolved Organic Compounds) levels lower, in between water changes.