The only "mechanical" filtration I use on ony of my tanks is actually before the skimmer via a 100 micron sock that all the water going into the sump goes through before entering the sump. I change/clean this sock out once a week unless i stirred anything up myself by chance...then i will change it out a day after the stirring occurred.
Im actually doing some experiments at the moment to possibly eliminate the sock as well.
UV last in line on my setup but was thinking of a break off bypass to a carbon filter when ever I need it. else I go from 25-50 micron no pressure then to 50-100 n pressure then uv and back to the tank my second is a sock with a 100 cd container going from 25 to 200 then drip from the bottom to the sock stuffed with bioballs.
machanical filtration can be a benefit but it takes much more maintainence. The bacteria on LR process, the skimmer removes and the mechanical just traps. Trapped waste, detritus just continues to break down and leach all its nasties into the water untill its removed. Thats where the maintainence comes in. You have to keep up with it faithfully to keep some stable water. Let it go and the cons quicklly outway the pros.
Ive tried a filter sock, it trapped alot of gunk. Personally I dont want something else to clean and the LR and Kick butt skimmer do all that is needed! I do run carbon though and that is also changed out frequently.
The benifit of Bio-galls is the bacteria they are designed to harbor. Sponges will do the same but they serve the main purpose of catching the detritus. Both collect poo and that is whay they both have issues and are not so recommended in a reef tank unless you are willing to do frequent and regular cleaning. Otherwise they can become nitrate factories as they hold detritus and allow it to decompose and rot in the water column.
Personally I just use carbon. It still collects the detritus but its nature makes it able to absorb toxins and nutrients as oposed to spnges, filter floss etc. But, at some point carbon will also become saturated and begin to leach nasty stuff back into the water. There are some who believe that carbon is bad and strips the water of trace elements and such. With regular water changes it is not an issue in my opinion as I have used it 24/7 with no ill effects. As with many things in the hobby, we are left to make our own decission based on overwhelming numbers of opinions and some strong data that can be found! Carbon is good for "polishing" the water if it gets murky and does so very well!
thanks.I have had the bio balls in the current filter and wanted to avoid a mini cycle in the system because everything is doing great for the three months the tanks has been running, and i did not want to change too much at once.
If you plan on removing them (widely recomended for a reef) then do it a bit at a time. That way the bacteria on your rock will be able to adjust and multiply so there is no real drop in bio-filtration in the tank. Youll be fine doing it slowly!
Oh, after reading th other responses i forgot i do do another form of mechanical filstration as well.......i run carbon through a canister filter 2 weeks on.....two weeks off and change the carbon each time.