high nitrate level

[Richard]

No, it doesn't have Nitrates

LOL, Good one. Neither does mine.

[gjuarez]

I love this type of thread, where two aquarists with lots of knowledge debate. I feel it is when I learn the most. Keep it coming, wheres Gary?

[NaCl_H2O]

To be honest, my fuge probably has more to do with my water quality than the Bio-Balls.

When I put this system together I just put in some of everything that worked for me so well in my 125g and added to it. The way I figure it, all of these things contribute in some way to the chemical/ecological balance and I doubt that any of us fully understand how they interact as a "System". I do have a very large wet/dry filled with Bio-Balls and mechanical filtration (floss). Also have a large fuge with a DSB, and a DSB in all the tanks, plus a VERY generous supply of live rock, lots of sump space, and an aggresive skimmer. Bio-load is reasonable, but not heavy, I feed as little as I can get away with, and do 20% water changes every two weeks.

Richard's peleted Charcoal bed fuge is intriguing! I have considerd changing my small frag tank into one of these?

[bigdscobra]

I feel the same way,

I have a fuge that is jammed pack with cheto and a wet/dry above my sump. Also two biowheel filters that I use to add carbon W/O the wheel. A little bit of every thing seems to work great. Now only if I had a chiller ;)

[matt]

Matt, Are you saying a refugium can serve as a substitute for the wet dry filter?I would assume then one runs the refugium simultaneously for a while before giving up the wet dry trickle filter? If I have a 29 gallon tank, what size refugium would do the work of the wet/dry filter?

The wet/dry filter is kind of a dated type of filtration; it's designed to provide habitat for denitrifyng bacteria that would normally not exist in an "old style" salt water aquarium with no sand bed or live rock. It also does a good job of aerating the water. But, if you have lots of live rock, a decent sand bed, strong water flow, and a skimmer, you don't get any benefit from the wet/dry, as you have created the environment in your system that does all the things it would do, in a more thorough manner.

The wet/dry, or more specifically, the bioballs in it, does not "create nitrates" but, if it's the primary type of bio-filtraton you have, nitrates will tend to accumulate because you don't have low oxygen habitat for the bacteria that process nitrates into free nitrogen. (There used to be some sort of anaerobic filter for that, too) This is where the sand bed, and refugium, can really help.

The refugium simply acts as a habitat for growing macroalgae, which will consume nitrates and phosphates from your tank. It also provides habitat for lots of small animals and larvae, which then get picked up in the water flow and delivered to your tank, where they can be eaten, thus lowering the amount of food you have to add to your tank. Plus, if you run the lights on a reverse cycle, the macroalgae photosynthesize at night, keeping O2 levels up in your tank and helping to stabilize ph.


You probably can easily convert your wet/dry into a refugium, simply by removing the bioballs, keeping the water level in it nice and high, and putting some sand and live rock in it. You'll need to light it, of course; power compacts work well for that. Once it's set up and stable, you can grow macroalgae like caulerpa. If you have a well stocked tank, probably the caulerpa will grow really fast. Then you periodically harvest it, and in this way remove the nitrates and phosphate from your system.

For a 29 gallon tank, a 10 gallon tank would work fine as a refugium, or better yet, a 20 "tall", if you don't want to try to convert your wet/dry. It doesn't really matter; just get a decent water volume and good light.

Hope this helps

[matt]

Oh yeah, I forgot one thing. If you're currently using bio balls, you should remove them gradually to make sure that you give the bacteria time to colonize on the live rock and in the sand. Removing all of them at once might put your tank into a nitrogen cycle, which would really suck for the animals. If you have lots of live rock and a fairly mature tank, it might not make any difference, but probably it's best not to risk it.