1. Sand Questions. With the sand bed... If I get 9-11 pygmy cories (Yay! They're so small you can get many!) will they shift the sand bed enough with their barbles to keep algae off (I have EXTREME lighting)? And what type of sand is heavy enough that it doesn't float around constantly and get stuck in the filter but looks really awesome? Something like this...
Cories are omnivores. They need sinking carnivore pellets for food. Yes, they do eat some plant matter, but not a signicant amount. They do dig quite a bit in the sand though. There are many types of sand out there... that's a whole other topic in itself.
I used flourite black sand in part of my 55 gallon tank and my 10 loxozonus cories have no problems digging around :) It looks AMAZING but you have to RINSE IT VERY WELL before use! And no, it didn't turn hard with the pressure of the water....
Put the sand in a bucket (about 1/3 full). Fill the rest with water. Swish it around, pour out the cloudy water. REPEAT until the water is crystal clear when swishing the sand around :)
2. Cycling Questions. I've probably had my cycle going for a week. The ammonia is at roughly 6 PPM, but there's still no nitrites. How long does it take on average for the bacteria to start forming in a tank that's using the shrimp method and isn't being seeded?
It's getting a bit annoying that every time I test the nitrites my dad calls out "You need to introduce the bacteria! It wont naturally form!" And then I have to tell him "Yea, it will. It just takes several weeks."
IT WILL NATURALLY COME!!! AND IT CAN TAKE SEVERAL WEEKS
There are 2 different bacteria colonies involved in the nitrogen cycle. These bacteria -- along with MANY others -- are present in the air and will naturally come into your tank to feed on what they want > ammonia and nitrite.
Some stores sell "bottled bacteria" but this stuff is SOOO hit and miss. Maybe this is what your dad is referring to? I personally would NOT recommend it to anyone.
So...The first bacteria (Nitrosomonas)
converts ammonia to nitrite and is reddish in color. I would recommend cranking the heat above 80'F... maybe even 84'F as the bacteria multiply faster at higher temps. Also, the bacteria don't need light, but they DO need dissolved oxygen and lots of it. You could lower the water level in the tank so the filter creates more surface agitation -- and if you have one, crank the air pump/stone to high and move it near your filter's intake.
The second bacteria (Nitrobacter)
will start to form once there is sufficient nitrite to feed on and convert it to nitrate -- and is brownish in color. Same applies to this bacteria for temp and O2.
Each of these bacteria take nearly 20 hours to double their population, so as far as bacteria go... they are VERY SLOW GROWERS. They also prefer a pH above 7.5 and will not grow well (if at all) with a pH below 6.5
Hang in there... if you feed them (ammonia)... they will come!