Greetings;
It seems as though the LFS (Local Fish Store) you have been dealing with has given you some bad advice, whether through greed or ignorance, at this point doesn't matter. I know as a newcomer it is very hard to sift out the good with the bad; the only way to make an informed decision is to arm yourself with knowledge. Recommended reading: The Conscienctious Marine Aquariast by
Bob Fenner. The Natural Reef Aquarium by
John Tullock..or just about any of his books dealing with beginning reef keeping.
1) Anemones are not for the beginner or for newly established tanks. They need specific requirements of light and food and usually have a miserable survival rate in home aquaria. As you can attest by the ones that have already died in your tank. Clownfish do not need an anemone to be happy or survive. I suggest you return the anemones to the place you bought them.
2) Your tangs are most likely not going to fare well in your tank either. These fish grow quite large, need lots of space, and don't often do well housed together in even a large tank. Even one tang in your tank will not fare very well; if it survives the stress of a new tank that is basically too small for it without falling prey to disease it will very soon need a larger tank. Depending on the species of tang, a 75 gallon tank is a minimum. Again, returning these fish to the place you bought them or trading them in for credit is the best option here.
You need to watch the stocking level on your 39 gallon tank as well. If you are going to have corals, three small fish is probably your limit. If it's going to be fish only, you might be able to house one more or so, depending on the type of fish and the filtration and maturity of your tank.
As far as what to test for in your tank, typically you need to test for Nitrites, Nitrates, Ammonia, pH and Alkalinity. What kind of test kits do you have? If you have taken any levels with them what are they?
Sorry if this isn't what you wanted to hear but we'll help you as much as we can. If you could post some specifics about your tank regarding filtration, lighting, water movement, etc. it would help us help you.
~Alice
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Reefkeeping is my life; I can't afford a hobby too!
