Whats the story behind undergravel filtration for saltwater aquariums?

Question

Is undergravel filtration antiquated and not worth messing with? I have been told that it is a lot of trouble to clean and other devices will work better.

Can undergravel filtration be used with other devices(a power filter) and if so how effitive is it? Could undergravel filtration + power filter take the place of a good protein skimmer?

I want to have either an all fish(hawkfish + 1 or two other fishes) or fish + invertabrete(shrimp/goby and two other fish, maybe a butterfly or tang).

Answer 1

It's not used as much anymore, but it can be used with other filters. The advantage of using it is that the water flow through the substrate is increased, so you will get better biological filtration. The downside can be that you get a buildup of detritus or anaerobic areas forming under the filter plates. you can avoid that by using a reversible powerhead to move the water down the tubes and up through the gravel - the opposite of how they're normally run.

An UG filter won't totally replace a protein skimmer - they work in different ways. The UG will give better biological filtration by moving the water through the substrate so the bacteria have better contact with the ammonia and nitrite to convert them to nitrate, but the nitrate will build up in the tank. The protein skimmer uses fine bubbles to remove dissolved organics (from wastes and food) by raising them up to where they are deposited in the collection cup so they're out of the tank altogether. A good skimmer will do more for the tank, but will be more expensive.

Here's a link to an online article about using UG filters for saltwater by Bob Fenner, author of "The Conscientious Marine Aquarist": http://www.wetwebmedia.com/FWSubWebIndex/fwugfiltr.htm

I run some UGs in my freshwater, but not as an only filter. I don't have them in any of my current saltwater tanks.

Answer 2

From my personal experience with that type of filter, Don't use it. They are fine at first, but then the junk that gets under there, stays under there.Sure you can gravel vac but it doesn't remove all the debris, so it sit under there building up. Until one day you notice a huge drop in your P.H., then you notice some clouding, then your fish start dropping like flies, you do water changes but nothing helps, you use buffers, nothing helps, you are freaking out!!! You have just now learned what crashing your tank means. For salt tanks use the berlin system, lots of live rock and a few power heads and a protein skimmer, for added filtration I like using a cannister filter, that way you can add bio media for a good stable bacteria bed.

Answer 3

i have a power filter running along with an underground filter in one of my tanks and just a power filter in the other. The undergravel filter keeps the tanks water pretty much crystal clear all the time while my other tank that doesnt have one gets cloudy very quickly. It is a pain to get all of the crap that builds up under it out but even if you dont get all of it out the water is still very clean and looks nice.

Answer 4

JUST DONT USE IT JUST DONT