Rodney here,I had a customer call yesterday about running a tank without any filtration of any kind,except a protien skimmer. I have seen this maybe a couple of times since I have been in the hobby and it ran fine, but it seems the chance of something going wrong could be greater. My advise was that with all the technology the industry has today it might be better to take advantage of it. But did say that with maybe a three to four inch sand bed,a decent amount of live rock, good protein skimming, and overall good husbandry it is very possible. But I thought that I had better take the question farther not only for me but for future questions like this one. Any advise or comments that you have or anyone else for that matter would be greatly appreciated. Are these types of systems fine or is it better to have a sump or some sort of adequate filtration. And as a side note I have taken your advise that you gave me on the pics of the 90 gallon and using it on the 125. I have been reducing the amount of corals that I had in the tank and am allowing for proper growth of the corals that I really want. I have not started using ozone yet, still a little leery of it, but it is in the works. Hope that the end result is a good one, very large beautiful colonies.

Rodney 

a good question. Very glad you asked my friend. And much like "whay kind of lighting should I buy" questions... it cannot be answered without a lot more info (bioload and intended husbandry/water changes in this case) or without making some huge presumptions.

That said... you have made some mistaken assumptions here, bro. To say the tank lacks "adequate filtration" (vis a vis a man-made filter) is on gross error. MOst living substrates have superior nitrifying faculties compared to most man-made filters. So yes... a system like this can work. It actually had worked for many thousands of folks for decades (back to the 1960's) and in collecting old aquarium books I/we see many folks kept natural displays without anything (predating electric air/water pumps or skimmers, etc) save for a daily walk to the shore to get new seawater for a daily water change.

In fact... my entire greenhouse op fits this description of "natural filtration". Heavy coral bioloads... and a skimmer on most systems, but nothing else besides a DSB and small amount of live rock in some tanks. This has worked for me for over ten years.

The key to success with such natural systems is a low bioload and regular water changes (and/or other aggressive nutrient export)

But then again... that is the key to success to any marine aquarium IMO.

As for your ozone fears, Rodney, they are completely unfounded I promose you. Aquarists commonly have very irrational fears about it. Do start a new thread if you want to work through it and let me/us all support your exploration and address of concerns.

kindly, Anthony

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Anthony Calfo