Saltwater set up, doing ok?

Question
QUESTION: Hello I messaged you awhile back about setting up a salt aquarium ^^, I just set up a 33 gallon cube saltwater tank. Yesterday.

I mixed my own saltwater for about 40% of it and topped off the rest with already mixed salt water from the store I work at, It comes in a box. I measured the level specific gravity yesterday and it was at 1.022 exactly, and using my quick dip strip kit all the levels of Nitrate/Nitrite/PH and all that good stuff were right on. I also added a product called bio-zyme to help the cycling process along.

I am set on waiting 2 weeks before I try to add just one fish which will be a damsel.

Now I've heard mixed mixed things about using filter media. I have a Bio-Wheel filter for 50 gallons since I was told it's good to have more than just enough to filter the 33 gallons. But a few places I have read to Not use carbon filtration by any means...and then there are people who told me it's fine to use carbon. I'm so confused.

This morning when I tested the specific gravity it was 1.021...is this kind of a change normal? and Is it a bad change?
Also what is the best way to fix that...do I take the water already in the tank out and mix new water that has 1.022 SG and put it back in? Or do I add salt directly into the tank little by little until it goes up...if you could tell me the best way to do this, it'd be much appreciated. Thanks!

PS: If it matters, I have a 50% white sand and 50% coral (almost looks like little shells) as the substrate.

ANSWER: Hi Krysta. It sounds like everything is going good. What most likely happened with your S.G. was that when you tested it yesterday the temperature was not quite up to where it should be. The S.G. will go down as the temperature goes up. To fix this you can take out about a gallon of your water, mix in some salt to that water to get a specific gravity higher than what you want it at and add that to the tank. In 33 gallons of water to raise your salinity .001 You will probably only need to add about 1/2 a cup -1 cup of salt. There is nothing wrong with the S.G. that you have and you may want to consider keeping your tank a little closer to natural seawater which is 1.024-1.027.
I am one of those that believe there are many benefits to using activated carbon in any system. Carbon not only absorbs chemicals out of the water but will cut down on the amount of dissolved nutrients in the tank as well. People who do not use it are asking for trouble. Some invertebrates can release toxins into the tank. Carbon will take care of them before you even know that there has been a toxin released. Also if something were to accidentally fall into the tank(I had this happen with a candle that I set on top of the tank so my cats wouldn't knock it over and I ended up Knocking it over myself) the carbon would help absorb any chemical that might have gotten into your water. Carbon has been used in tanks as long as there have been tanks kept and it is a shame that there are those out there who actually belive that it is not beneficial. Carbon will also keep your tank water from yellowing which is a natural occurring process from the build up of certain acids that can accumulate in your tank. There are only a few drawbacks to using carbon and they are that carbon will absorb some of the good trace elements in seawater, like iodine and magnesium, as well as the bad and if you purchase low quality carbon it may leach phosphate into your system causing more algae to bloom. The latter can be taken care of by only buying high quality activated carbon and not the cheap stuff sold as regular carbon and even charcoal. Carbon is so effective at keeping your tank water crystal clear that it may mask the fact that a water change is needed. So never rely on how your tank looks for judging weather a partial needs to be done or not. Keep a regular cleaning schedule and test often. The benefits far outweigh the potential problems and there is no reason to omit it from your system. Be sure to use a carbon that is labeled as phosphate free. Carbon will not in any way harm the inhabitants of your tank. If you are planning on doing corals you may want to simply add trace elements to your system to ensure that they are not being depleted by the carbon. Carbon should also be changed once a month to ensure it remains effective.

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QUESTION: It's good that I can have the carbon then...
I was just looking at a suplement today that replaces the good stuff taken out by the carbon and stuff.  But how do I tell if I'm low on those things?

Also what is a good temperature for the water to cycle it at? I know I will probably have to adjust it for fish.

Answer
The supplemental dosing of trace minerals only needs to be done if you have invertebrates like corals that rely on these elements for skeletal development. Fish do not require these in heavy enough concentrations that would not be replenished by simply doing a partial water change. You can test for most of the trace elements needed but as long as you are following the manufacturer's instructions you should be fine. This is only going to be important once your tank is fully stock with corals and other inverts. It is not important during the cycling. Be very careful not to overdose the tank on trace minerals either. This can have an even worse effect on corals than not enough of these minerals. Also keep in mind that dosing needs to be done mostly only right after fresh carbon is put into the tank. After your carbon has been in the filter for a week or two this shouldn't be a problem. I dose my tank every other week with a trace mineral supplement and I do a partial water change on the other two weeks that I am not dosing. This way every week my tank is getting fresh trace elements put into the tank from either the additive or the freshly mixed up salt water(salt mixes contain all the proper levels of these elements and most of the time if you are in doubt as to weather or not they need to be added simply doing a partial water change will be more than enough to replenish them. Don't worry too much about the trace minerals in your tank. The carbon will not totally deplete them unless you are not doing your partial water changes frequent enough.
While some bacteria can speed up their reproduction rate with the change in water temperature it is best to just keep your tank at the same temperature you are planning to always keep it at. I would recommend around 80 degrees for cycling and for the life of your tank. No need to change the temp. during cycling.