That's a very circumstantial question. Depending on: the driver you choose, the LEDs you want to run, and if you run them in series or parallel is what will determine how many LEDs you can run.
There are a few numbers you need to understand to figure this out. First, voltage. Second, current.
Your LEDs will have a forward voltage drop. The ones I have used, were about 3.6v. This number multiplied by the number of LEDs in a string, will tell you what voltage driver you need. Typically, you will design your string voltage around the driver you choose. But you will need to cross-reference the driver and LEDs to figure out what works best for you. Let's say for example you want to run strings of 6 LEDs that have a forward voltage drop of 3.6v. 3.6v * 6 = 21.6v. This means a 24v driver (and power supply) would be adequate for this. You could not obviously use a 12v source. Moving on, let's account for current. My LEDs have a maximum current of 750mA. This is per string. A 1A driver/power supply would be capable of driving those, but what if I want 6 strings? That's 750mA * 6 which equates to 4.5A. Now, this is of course at full blast and I don't run LEDs at 100%, they are actually at 50%, so I'm only pulling 375mA per string. With those concepts in mind, you should be able to figure out how many LEDs you can run and what drivers you need to run them.
I have not used the typhon controller but if you bus the PWM signals together you can control multiple strings. The controller I built only has a blue and a white channel, but I have that bussed into 8 blue channels and 4 whites.
Also, I would recommend you build your fixtures modular. I intended to build a big 6' fixture and then opted for 3 20" units instead in case I ever needed them for a smaller tank or different setup. I could always add another unit or remove one. Thankfully I did that because my 210 broke and I now have a 4 foot tank.
