To supplement the other answers:
...decreasing the chances of any intruder to find out the hashing system used...
If you don't pad your hashes to make them of equal length, the attacker can figure out which scheme is used. That would unnecessarily increase your complexity factor (and might even confuse your own code if not done right).
Furthermore, you are dividing your users in three categories:
- The less technically-inclined
This class of users will get irritated, confused and potentially feel stupid. Interesting article on this but the point is, they might end up hating you. Or they might escalate to know-it-all's.
...who believe a simple hash function is all it takes to make a website hacker-proof. See the Dunning-Kruger effect and decide if that's your target audience.
- Those who know what they're talking about
The people sites like this attract (except for me, I'm more of a know-it-all). They will avoid your website like the plague, and if they absolutely must register to see something, they'll use Bloody Vikings! and
PASSword1 as their password, and never set foot in your website again. They might even send you a strongly-worded email about your policy (if you're lucky), or even use you as a counter-example in their next presentation.
Bonus: You are also violating Kerckhoffs's principle by relying on the inability of the attacker to guess the applicable scheme. You want to make his life difficult - that's why we use salts and good password policies for. Enforcing the latter will get you much better results.
That said, as Alexandre et al says, use scrypt or bcrypt instead. This and this question on Security.SE might help you decide on the work factor.