im gonna use play sand.

Go to Home Depot, buy their KolorScape White Play Sand in a clear package with blue blocking and white lettering. It like $4 for 40 lbs. it is exactly the same as the old southdown, a sugar grain sand, work's great. I would how ever recommend you buy a least a small bad of some larger grain argonite to add to it.

 

kolorscape, ill look for it.

 

found old castle sand it should be at home depot. its online at least.

 

Beyond the dustiness and general unsuitability of play sand due to sharpness, you're going to be missing out on the amazing pH buffering and calcium-adding properties of aragonite. I seriously have been running a tank for 2 1/2 months without doing a single thing to change the pH or calcium levels, which I would have to do every 3 or 4 days (for pH) with similarly-sized freshwater tanks. Aragonite is enormously convenient because of this, and I personally recommend some kind of aragonite sand, whether it's play sand or "fish sand".
I also recommend getting at least 1 small bag of "live" sand; it'll help your cycle start up just a little bit faster. I'd liken it to gravel soaked in Cycle, in freshwater terms. Don't run the protein skimmer when you put in any sort of live sand, btw. You don't want to skim out the bacteria you bought lol.

 

I keep 6 tropical and 1 marine tank in use at all times and recently decided in 1 of the tropicals to use play sand. First of all the dirt I washed out of it before putting it in the tank was unbelieveable. I rang my daughter and warned her about my grand children playing with it. Next after carefully putting it in the tank and gently filling in the water there was a lot of fine sand floating around. when I started the filter up there was a complete dust storm which I thought would settle down. Five days later with very little improvement I gave up and cleared out the tank and started out again with a new substrate. Now all of this was with a low turnover pump in a tropical tank setup, I dread to think what a marine setup would have done with a high turnover of water. Sorry save your time and wait to you can buy proper sand or agronite

 

Not saying that aragonite doesn't buffer pH but as far as the Calcium goes weather or not your going to have to add calcium or not entirely depends on how may "Calcium" using creatures you have in your tank and on how many and how much water you change when you do your water changes.

For the first 6 months I had to do nothing to my 75 gallon reef, then I started adding more and more SPS and Clams... Now I use both 2 part and kalkwasser every week to keep my levels up and I do water changes every week. But when it comes to my seahorse tank I have never added anything sine I put it up 2 years ago. this is because there are very few if any creature that use it up.

And why spend 20 or 30 bucks for a bag of sand that depending on how long its been on the shelf have bacteria in it. Best way to start is to get a cup or two of sand from another reefer that you trust. you will get more "good" stuff in those 2 cups than you ever will in multiple bags of "live sand"

Or if thats not you thing them get some "bacteria in a Bottle" There are tons of products out there now that you can buy that have live cultures of bacteria in them. While I have never used any I have heard lots of really good things about it.

 

I was under the impression that as Calcium levels lowered, it lowered the pH, which speeds up the reaction in Aragonite, thus releasing Calcium and raising the pH. I realize that in a SPS-heavy tank it won't be enough, and that's why people use Aragonite in a reactor setup, but it should be a good buffer to start with.

As for live sand, even if 90% of the bacteria is dead, you're accomplishing 2 things with the live sand. You're seeding the proper bacteria, which is undeniably a good starting point. Also, you're providing dead bacteria for a mini spike in Ammonia, which is a perfect time to add your first bits of living things to the tank right after. Your new life can take up the overhead given by the dead bacteria's decay in ammonia production, which in essence should let you stock quicker with less stress on your first few fish.