Need some advice on setting up a tank

[louiemarsh]

All,

Can someone please explain why a wet/dry filter produces higher nitrates? I might be wrong but I think the bacteria live better in that enviorment then in a completely submerged enviorment.

Also, why did the hobby move away from the crushed coral substrate? I actually started using sand a few years back because I liked the lokk but was kinda thinking of setting my next tank up as a bare bottom or thin layer of crushed coral for ease of cleaning.


I guess my last question would be about surface skimming. Is that 100% needed? What if you tried to take the water for the lower portion of the tank instead of the top? I assume there might be a film buildup on the water surface?

Any advice would be great.

Chris

 

[xxaquanutxx]

I dont have time to post, so hopefully some one can chime in a little later with a deeper explanation... Basically it comes down to 2 types of bacteria that have 2 totally different needs and produce 2 different effects.

 

[Blown 346]

A wet dry filter will increase nitrates from the bio balls that are used. Bio balls will hold and trap detritus( fish poop, food).

Crushed coral will also do the sae thing as mentioned above, if you have a fish only tank than CC can be used since fish aremore tolerable to nitrates than corals and inverts.
I never clean my sand, I have crabs and snails to that for me, with crushed coral, it would b very difficult for those same animals to do there job at cleaning.

Surface skiming isnt completly necassary but it does help in removing proteins that will build up on the surface of the water.
By taking water from below the water line to skim, you will be taking out proteins etc, but not as many as if you were to take them from the surface.

 

[louiemarsh]

Thank you blown for the advice. If it just has to do with fish poop/food then I will not have a problem as my filter has a huge settling chamber before it enters the biolgical section.

 

[MCary]

There is more to the wet-dry thing suspected than trapped detritus. I'm going to shoot some stuff at you from memory. It might be better to research it for a better understanding. For one thing, the bacteria that covert nitrite and ammonia to nitrate are much more active in a highly oxygenated environment. Initially that was the benefit of the wet-dry system and they were incredibly efficient. Since the by product of these bacteria is nitrate then the more efficient the bacteria the more nitrate produced. The question is, how can they produce more nitrate than the available nitrogen in the ammonia and nitrite. I have heard that some suspect that they pull some nitrogen from the air. But since the bioballs only raise nitrate significantly if they are not submerged and since biowheels do the same thing and do not collect detritus, it is probably not a waste issue.

The crushed coral main issue has been address. Because of its large size it can collect waste that slips down into the cracks. Other issuses is that it is too large for sand sifting critters. And because of its large size it does not produce an anaerobic layer for the reduction of nitrates.

 

[louiemarsh]

Thanks much for the info. The pulling nitrogen from the air might make sense and thanks for the crushed coral observation