You don't need anywhere near 50%
LS. Use 100% of the playsand. Get some uncured
LR. Get a lot of base rock (hirocks.com or
Reef Rock from ThatFishPlace.com.
Place the base rock on the bottom of the tank in the arrangement you want. Dump in the dry sand. Cover the sand with trash can liner and partially fill the tank with s/w mixed from
ro/
DI water. Remove the plastic liner. Continue the aquascaping with some
LR. Complete the filling of the tank. Let the tank cycle.
The sand will create a cloud in the water column which will settle as the sand gets coated with bacteria. The bacteria will come from the
LR. Alternately, you can hold off on the
LR for now by adding a cocktail shrimp to start the cycle. See
How to cycle your tank with out the use of fish for information on how to do that. Once the tank has cycled prepare for a 25%-30% water change. Remove that amount of water and add some
LR, then fill with the freshly made s/w mix.
Your tank will start a new mini-cycle depending on if you are using fresh rock from liverocks.com or uncured rock from other sources (Walt Smith, etc.) You can keep this cycle by doing
PWC every day or as needed (as noted by testing for ammonia, nitrite and nitrate).
The best part is that the sand will be seeded with the critters that come along with the rock (worms, copepods, amphipods, etc.) making a healthy sand bed.
You do want to have a powerhead or two going while you are cycling. You can run a skimmer but your cycle will take longer. I would hold off on the skimmer until the
LR went in.
When your tank is ready you should have 10x-20x water flow per hour. FOr a 90 that should be 900 -1800
gph flow from all pumps. Arrange the pumps so they point to each other or to a common spot e.g the center front pane of glass. This will cause a chaotic water flow which is what you want.
