How to reduce/control Nitrates

[lorenk]

I got a question from someone at work regarding how to lower nitrates in his tank. This is what I said back...please correct me or add. Oddly enough, I've never had nitrate problems but maybe because I do frequent water changes...but that's becoming an issue as my tanks get larger.
<p style="text-align:left;"><span style="font-family: Tahoma;"><span style="font-size: 12px;"></span></span>
<span style="font-family: Tahoma;">He has a 95g tank and I've not found out all the details yet, but there should be some general nitrate reducing techniques regardless of size and configuration.</span>

<span style="font-family: Tahoma;"><span style="font-size: 12px;">1) Skimmer...use an appropriate sized skimmer and make sure it is configured correctly.</span></span>
<span style="font-family: Tahoma;"><span style="font-size: 12px;"></span></span>
<span style="font-family: Tahoma;"><span style="font-size: 12px;">2) More Live Rock and Sand...how many lbs or Rock do you have? Should be 1.5 to 2 lbs per gallon. </span></span>
<span style="font-family: Tahoma;"></span><span style="font-family: Tahoma;"><span style="font-size: 12px;"></span></span>
<span style="font-family: Tahoma;"><span style="font-size: 12px;">3) Refugium...this is essentially a small extra tank (or sometimes built in with the sump) that had macro-algae (basically plants). The benefit of a refugium is a) more water volume b) algae assists in denitrification and c) they are typically on a reverse light cycle which helps stabilize PH. Plants basically eat the nitrates to grow, but only at low levels.</span></span>
<span style="font-family: Tahoma;"><span style="font-size: 12px;"></span></span>
<span style="font-family: Tahoma;"><span style="font-size: 12px;">4) Water changes...how often are you doing water changes? This is the sure way to remove nitrates and actually the main reason for water changes (and to add back in nutrients).</span></span>
<span style="font-family: Tahoma;"><span style="font-size: 12px;"></span></span>
<span style="font-family: Tahoma;"><span style="font-size: 12px;">5) IF you have bio balls, the common term for those are "nitrate factories" and many people do not like them (I don't have any). They need to be changed or cleaned regularly or they will end up creating more nitrates instead of reducing them. I threw mine out and use live rock rubble.</span></span>
<span style="font-family: Tahoma;"><span style="font-size: 12px;"></span></span>
<span style="font-family: Tahoma;"><span style="font-size: 12px;">6) Nitrates occur naturally in tap water, along with other nasty things so avoid tap water. </span></span>
<span style="font-family: Tahoma;"><span style="font-size: 12px;"></span></span>
<span style="font-family: Tahoma;"><span style="font-size: 12px;">7) Do not overfeed your fish...yeah, you know that.</span></span>

 

[jessezm]

Those are good guidelines. The best way is prevention/maintenance, however, some people find themselves discovering late in the game that their nitrates are way high, and the above are only truly effective once the problem is brought back down to reasonable levels.

A few strategies that seem to work:

For the inexperienced, but wealthy--a sulfer denitrator can pull down high nitrates significantly in a few weeks/months

For the more experienced, dosing with vodka/sugar as a carbon source can be effective. This requires much more depth of understanding to do safely and successfuly.

Other than that, sandbed maintenance and avoiding the settling of detritus can be important as well.