Tracking nitrate sources...

[Sk8r]

[with thanks to Funkejj who suggested this topic]

First of all---general things to suspect, on the very big scale: you should have started your tank with ro/di water and should be using only ro/di for a whole lot of reasons involving what's IN tapwater that shouldn't be. If you didn't use ro/di, a program of weekly water changes WITH ro/di-based saltwater will gradually help eliminate various problems that come in with tap water. ]Water conditioners only remove the chlorine/chloramine. They do not really 'condition' the water in any sense of readying it for marine use. Conditioned tapwater CAN be used in a screaming emergency, like a broken tank. Otherwise---not.]

Then: insufficient live rock. You need 1 lb per gallon, and lacy, holey rock is more efficient than, say, solid, heavy rock. It has more surface area. If all your rock is very solid and heavy, you may have enough poundage, but not enough surface area. The water passing and circulating THROUGH the live rock gets bacterial action that cleans up the nitrate.

Now: you're using ro/di and you have good live rock. And you still have a problem: the next thing to do is, start at your pump as a water drop---where do you go? up a pipe to your tank. You're slightly nitrated. You circulate through the live rock and you're clean again: all the nitrate you came in with has turned into a bubble of nitrogen gas and floated to the surface. You're clean, clean, clean.
You exit the tank via the overflow---and?
You go down a tube.
If your path lies through a filter sock that hasn't been cleaned in forever...you're dirty [nitrated] again. Many reefers opt not to use filter socks at all, because they're just one more job to do that for an lps or sps or anemone tank is actually taking food from the mouths of your corals.
If your path lies through a cannister filter instead of a sump---problem. A cannister filter isn't live rock and doesn't contain the right bacteria to turn waste into nitrogen gas. If full of crud, it's nasty. They have to be cleaned often, often, often.
If your path takes you into a sump through bioballs, a wet-dry filter, etc, problem. Again, nice bacteria, but not the bacteria that turn nitrate to nitrogen gas. You pick up the nitrate here.
if your path takes you past an old forgotten bag of carbon somewhere in your journey---problem, and you can pick up nitrate here. It's stopped absorbing things, it doesn't host the right bacteria, and now it's started releasing crud it absorbed right back into the water. This is a nasty habit carbon has once it gets full-up with whatever it absorbed, and how soon this happens depends on what it's been exposed to.
Now maybe your path goes through a skimmer, which removes amino acids, so you're a little better---but---you've still got a suitcase full of nitrate. A lot of it. You head through the pump, back through the rock where you lose the baggage...but as the filter medium gets cruddier, you come in with more and more nitrate, more than the rock bacteria can get rid of.

So what's the solution?
1. use ro/di
2. get enough of the right kind of live rock.
3. don't push your bioload beyond the capacity of your tank to HOLD enough live rock to totally do the job.
4. track the water path and look for nasty little areas your water drop passes through that could be adding to the problem. Sounds silly, being a water drop, but it's a way to conceptualize tracking the water through the total path, until you find the dirty little secrets in the water flow, the places your clean, pure water shouldn't be hanging out.
5. detritus pockets? floating brown fluff on your sandbed, or even worse, far worse, nasty dark patches you can see under your sand? Don't mess with your sandbed, and horrors, don't turn it over or vacuum it: that's what we did in the 80's, but we all used diatom filters to get rid of what we stirred up. The modern way? Get a true nassarius snail or two: they live under the sand, and they patiently clean even the nastiest corners, even get under the rock, and into the tiniest nooks where detritus might lurk. A brittle star, black and white, does a great surface job. If you have a tank above 50 gallons, one of the super-cleaners like a fighting conch is good---if you don't have plate coral: they can injure that accidentally.

A fish-only tank has a peculiar problem: you need space for your fish to swim, but fish are huge detritus producers. They often need particulate filters, that produce nitrate. They need extra rock but have no room for it. And they eat the cleanup crew.
One very good solution is a Remote Sandbed, ie, 20 gallon tank with a 4" sandbed and extra live rock and cheato algae AND a cleanup crew.

Frequent filter cleaning: a FOWLR takes work, a lot of work. Coral keepers may laze about with no filters and simply drip calcium into their tanks, [I jest] but FOWLR people have to keep atop the filter cleaning.

Add coral: they ARE living filters. LPS and softies suck up nutrient and filter the water. You have to have somewhat better lighting than a FOWLR, but if your fish aren't coral eaters, or don't eat a certain kind of coral, they might help. And you do have to drip calcium if you choose lps, but that's just a teaspoon of powder per gallon in your topoff.

Nitrate problems are especially common in FOWLRs, and nitrate has to be fought with filter changes, an RSB if you have room, and regular water changes. Fortunately fish tolerate higher nitrate---but you tolerate air conditions that aren't good for you, too. Do everything you can with skill, and that includes taking a clear, analytical look at your bioload, and at your future bioload as your fish grow, look at your feeding habits (don't make your fish fat: remember they're leading a sedentary life) and at your filtration. If the answer says: too many fish, too little skimmer for the protein going into this tank, I can't keep up with the filter changes---you need to make some changes. Remember there are two ways to run a tank---one, really relying on the live rock method, and one by just about daily filter changes. Even at a pound a gallon, live rock may not keep up with the load of a fish-only. Coral keepers can pack a tank with their prize specimens, and easily have 0 nitrate, with no filters at all. Fish-only keepers have to have clear space AND rock, and if the fish load is heavier than the rock alone can carry---they're going to have to have additional filters: the irony is that the least inattention to the filters themselves is going to up the nitrate. So it's a continuing battle, in which regular habits, easy-clean filters, and weekly tests (because fish grow, and with them, bioload grows), knowledge of the species (how big does it get...and a good circulation, blowing out those pockets where stuff can collect---are all important.

[Sitaga]

Nice info - thanks!

[SwampyBill]

Another awesome thread, Sk8r...Thanks.