Before starting on this new venture, I didn't think this would be the first issue I encountered. I thought water quality would have been the usual chestnut, but all 3 days of testing has resulted in positive results. The questions that have been raised range from live vs inert sand to substrate thickness. Let me explain my issues and what I have tried doing for each of them? Unfortunately most of theses issues came up after the facts and once I'd done the necessary research.
Live vs inert?
For my tank, the manufacturers recommend about a 3 inch covering of substrate. My local shop recommended that I use live sand, but it was ridiculously expensive. I was informed that it has live cultures that will benefit my tank and help with the breaking in of the tank. Having previously kept a tank that used an under gravel filter, I could well believe the benefits. However I couldn't justify the cost. So I ended up buying half and half, hoping to get a good balance between cost vs benefit. This got me thinking and then researching.
This is an interesting one that seems to have many people divided. Some people on the net believe by it while others say that its a money making scam. They state that cultures surely cannot survive if its been bagged for a length of time, which makes sense.
My personal thoughts are now, if you going to use live rock, then I don't think you need the live sand as the rock should have cultures that will benefit your tank. If you not going the live rock route, it may be beneficial to bring in some organisms using the live sand.
When should I put my sand in?
When I left the shop, we left with the water, tank and sand. But no rocks. We were instructed to use this and then get live rock in a couple of days. BIG MISTAKE. If you are going to aqua scape after having your sand in, you are going to need a soft touch and a lot of patience. This is because of the sand being disturbed and turning the water murky to the point of no visual. Having researched on the net, nearly everyone says that you should put the rocks in and then sand. The benefits are:
Better aquascaping as you can do it without muddying the water
Once you are happy with your aquascape, you can suck up any detris to prevent it from decaying off the bottom of the tank.
The sand will help anchor the rocks into place
By having no sand under the rocks, there is less likely hood of any gases building up under the rock that will get trapped and later released causing a severe deteriation of water quality (current concerns for deep substrate beds)
How thick should my substrate/sand be?
This had me and my wife puzzled and going back and forth. Most books, forums and shops recommend between 1.5 - 2 inches whilst my shop and manufacturer recommend 3 inches. Looking at the tank, 3 inches looked very deep. What's the difference. Deep beds substrates are a new thing, apparently and have huge benefits. I.e. organisms that grow in the sand can grow better and thus breakdown tank wastes for you. The bad news is that this gets broken into gases that can get trapped in the sand. When the bubble finally bursts, it can cause a severe deteriation of the tank water quality. What we decided to do, was take out some of the sand and go for a 2 inch thick bed as I am really not wanting to go down that route and rather rely on my filters to do the job. This was a huge operation as we already had rock and water in.