How long has the tank been cycled for?
Tanks normally go thru definite phases during and after cycling.
Algae blooms are common after cycling, and have their own phases.
Diatoms are usually the first phase after a cycle.
Don't worry about replacing, or "seeding" your sand and rock.
There is plenty of nitrifying bacteria to start your tank growing on the surface of your rock and sand since your cycle.
Although it's not necessary, a sump or fuge with additional LR
certainly won't hurt anything.
Between enough LR
, and your skimmer, you really shouldn't need anything else to get your water params in order.
, your tank is understocked on rock for effective filtering.
A minimum of 1.5lbs per gallon is recommended... more would be better in your case since you're only starting with base rock.
The more surface area for nitrifying bacteria to grow, and quickly, would be best.
As for your ammonia buildup, my best guess is that your tank hasn't grown enough beneficial bacteria to handle your bioload and feeding schedule yet.
As time goes on your ammonia from fishwaste, leftover food, and decomposing algae may be outcompeting your bacteria growth leading to more ammonia than it can process.
Of course, more info would help.
How often is your feeding schedule?
How much, and what do you feed? (flake, frozen, pellets, etc.)
How much, and how often do you do a PWC
What kind of water do you use to top-off? (RO
, tap, distilled, etc.)
Do you test for phosphates?
What is your PH?
I've read about sand crusting together before, but right now I can't remember what it indicates... I know it's nothing that's irreversible tho...
Don't be afraid to stir it up just as bugs, worms, snails, crabs, and fish would naturally do.
I'm guessing your tank is still new so you won't be in danger of stirring up any really nasty stuff that might cause a problem.
Speaking of which, do you have any sand sifters in your cleanup crew?
Nassarius snails are excellent for that job, and would help scavenge any leftover food that might be causing ammonia as well.
The veterans here are awesome and have helped me tremendously so you're in good hands... and BTW, welcome to AA!
Oops. There's been 5 new posts since I started this one.
Sorry if I repeated too much of what everyone else said.
I need to learn to type faster. LOL