Nitrate levels

[stan]

I added a live rock to my 4 year existing salt water tank about a week ago , at that time my nitrate level was above 50 before adding the rock I have since changed approximately 30% of my water but still have not lowered my nitrates below about 20, what can I do to help? nitrite and ammonia levels are do not show up on the test to be any at all.

[stan]

I appreciate your reply but do not know what DSB is and how to I get a Refugium w/Macro algae established?

[MikeP]

Stan, DSB stands for 'deep sand bed' one of the latest methods in fish/reefkeeping. Basically you have a 3" or more bed of sand in tank and it will be seeded with bacteria/organisms either from a culture or live rock. This helps break down wastes and lower nitrates (I think its a certain bacteria that does the nitrate consumption). If you look on Reefcentral Dr. Shimek has some faqs there or a fairly detailed description of the mechanics are to be found here:

http://rshimek.com/reef/sediment.htm

It's a pretty simple method but takes some time to establish and won't start working with just dumping sand in your tank. Correct grain size, depth and choice of fish/invertebrates are crucial to long term success. Note you can also put a DSB in a refugium or sump with a little forethought and leave a shallow sandbed or bare tank in display if desired.

Refugiums are separate areas safe from fish and predatory invertebrates where desirable algaes can grow as well as food for your fish (pods). Getting macroalgae established in the refugium not only lowers nitrates as the plants grow it also if done correctly will outcompete nusiance algaes like bryopsis etc from taking over since the macroalgae in the fuge absorbs most of the nutrients. Also it's a nice place to put a small coral frags, stressed fish etc for a short period of time. The idea though is to leave them basically fish/crab/shrimp free if you want zooplanktion to grow. Here are a few links to get you started on refugiums. Read them or not then hit us up with some more questions. FWIW I have 2 fuges running, one a hang on for my 46 and the other in the back of my 18 gallon nano-reef.

http://www.wetwebmedia.com/refugium.htm

http://www.geocities.com/Heartland/Valley/3389/reeftank/refugium.html

HTH

-Mike