Help choosing substrate?

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Best advice you'll never take as a beginner: T A K E  I T  S L O W

 

After burning out on the hobby after 6 or 7 years of multiple mixed reef tanks, when I went to set up an 8 gallon tank again a coupe of years ago I let it cycle with just rock for...at least 60 days or more. Just ran a short photo period and the stock pump (Biocube 8) and enjoyed the soft blue glow again. You have to really think of your tank as a living ecosystem before thinking about what kind of creatures you can keep in it. Fish should almost be the last thing you add, or coral depending on the type of tank you want.

 

You need a basic understanding of the nitrogen cycle, which it sounds like you are familiar with, but just need more experience with in practice to fully understand tank cycling. You also need to understand what belongs and does not belong in your water. This applies to the water you use to make saltwater, the water you use to top off, and the water in your tank. Testing for P04, nitrite, and nitrate is important, but you need to know what acceptable levels are of each (P04 - 0, nitrite - 0, nitrate - 0-25ppm ideally). Any level of P04 or nitrite means your cycle is not complete, and any addition of fish can prolong the cycle and endanger the animals you have.

 

This lack of knowledge is understandable since you are just starting out, but mine and everyone else's worry is that while you experience trial and error in figuring out how to keep a reef tank, you will be buying and losing fish unnecessarily. This can also lead to you burning out quicker because it feels like everything you are doing ends in dead fish and a dirty tank, just because you are moving too fast.

 

Since it sounds like you have already transferred everything into the 36 gallon tank (start a tank thread, we would be happy to discuss everything in that with you) I would do a couple of things that you are not going to want to do. 

 

1. Do not add any other fish to the system for at least 60 days while the tank cycles and settles in. Longer would be even better.
2. Do weekly 5 gallon water changes with RODI water ONLY for 30 days, then move to water changes every two weeks after that (Read up on how to properly mix saltwater and best practices for water changes, i.e. get water to correct salinity, buffer alkalinity, and having it at the same temperature as your tank before adding.)
3. Once you have undetectable P04 and nitrite, add a large CUC. A lot of us have moved away from hermit crabs as they can be more trouble than they are worth, but definitely add a bunch of snails to help clean up. Trochus are good for hard surfaces in the tank, nassarius are your sandbed cleaners. 

Once you get into the habit of how to care for the tank over the next 60 days, how to properly mix water and perform water changes, etc., you will have much better luck with the animals you want to keep later. Also as a byproduct of taking it slow with the tank, you'll have another two months of reading you have done on Nano-Reef in order to help grasp much better how to keep a tank. Ultimately we all want to see you succeed, and t a k i n g  i t  s l o w is the key to success in reefing.