Oh I see, well mine seems pretty healthy, and can you please explain what DSB/VDSB is?? I'm kind of new to the hobby
Not a problem.
DSB-deep sand bed. VDSB-very deep sand bed.
Most traditional systems have very little sand (1-2" deep) to no sand at all--bare bottoms. They require maintenance like vacuuming the sand or the "bare glass" periodically. The waste that is "uneaten" by your clean up crew will convert to NO3 and PO4. This can cause diatom "outbreaks" if not controlled of properly (algae/cyano). So, they become a maintenance nuisance. Thus, by the constant maintenance of the sand, you do not get the beneficial animals and bacteria that consume waste, NO3, and PO4 naturally.
On the other hand, DSB and VDSB (sandbeds of 3" +) act like natural filters. Similar to what your live rock does with the little animals and bacterias that live in it. Or what they call tanks with huge amounts of rock, the berlin method. Your rock is a natural filter that consumes waste, nitrates, phosphates, etc. Its the same thing with DSB/VDSB. They accumulate over time beneficial animals and bacteria that consume waste. So they help in the reduction of your nitrogen's in your system.
What people don't like about them is that over time, to much "uneaten" waste has accumulated. They eventually have to "replace" all of the sand. They cannot be siphoned because the introduction of oxygen will wipe out the little critters. Then you have an ammonia spike because of the die off. However, these people that say they are not worth it, are basing their decision on looks v function.
I have not noticed any difference with my sand, it is a DSB (3.5" deep). I actually think they look cool and are beneficial to all tanks. You can actually see the little worms that consume the waste wiggle around in the outside glass of your tank. I actually believe that the DSB has lowered my NO3 quite a bit now that it is fully colonized with little critters and beneficial bacterias. With DSB's, the benefit is also that you can add fish that "bury" themselves such as wrasses and some gobies. It is pretty neat watching my coris wrasse go night night and waking up in the morning--he buries himself when it is time to go to sleep or is threatened.
Here is a little bit more info on it:
http://www.wetwebmedia.com/deepsandbeds.htm