what is the highest safe nitrate level? isnt it no more then 20ppm?
In my book it is "0" or undetectable. My tank has never been over 10 ppm. If I see the nitrate level climbing I immediatley turn the RO/DI on and beging making a batch of water for a change. It also helps to have a fuge and correctly sized protien skimmer. Nitrates are deadly to fish at high quanities. It burns the thier gills and body, Imagine if you dipped your hand into hydrochloric acid. Thats probably what the fish feels like swiming around in high nitrate levels.
This is a excerpt from a Reef Keeping Magazine Article titled Aim for the Optimal, Not the Minimal written by: Nate Enders
"A sobering fact is that even the best aquariums most likely falls short of recreating a natural reef environment in many basic ways "“ light intensity, flow, availability of food, biodiversity and so on. Sadly, despite these obvious shortcomings in our practices, hobbyists are often only interested in the minimum requirements for keeping certain livestock. This is evident through many common questions on the forums: "œCan I get by keeping a clam under PCs?" "œWill a tang survive at least a few years in my 55?" In a way, this is only natural - hobbyists so interested in a particular specimen are hopeful that their tank can at least meet the minimum requirements to keep it alive. However, in most cases, these minimal requirements will fall far short of recreating that specimen's natural habitat. These two thoughts leave us with a moral dilemma: If it's just not possible to fully recreate nature, to what extent should we try? Successful reefkeepers know that the minimum is not acceptable. There is a difference between livestock that survives, and livestock that thrives. Even if we cannot fully mimic a reef in our home aquariums, making the best attempt possible will give our livestock the best chance of thriving, and will give us hobbyists a more enriching experience. At the very least, exceeding the minimum gives us a cushion in case of emergency, or in case the expert dictating that minimum was wrong!"
I agree with the broad intent "Aim for the Optimal' article. but do you have a source for the comments about nitrate burning gills? I know ammonia does. I've never heard this before. In fact, I've never seen anything, except anecdotal observations with a few species, that nitrates bother fish at all.
+1 Aim for optimal. Nitrate is non-toxic; however excessive levels show a short coming in your cycle. The complete cycle is to convert ammonia to nitrite, nitrite to nitrate and then nitrate to nitrogen gas. This is easily accomplished with a DSB or denitrification filter or simply skipping that step and manually removing the cause of the nitrate build-up with water changes.
Low bioloads and oversized equipment such as skimmers and mechanical filtration/sumps will help to process and remove waste before it can break down and raise the levels.