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Live Rock denitrification advice

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I have noticed that high nitrates are causing my pH to drop within my pico reef aquarium.

I was under the impression that live rock has a nitrate reduction process..

I thought that a high flow rate around live rock would drive nitrates deep within the rock enabling denitrification.

As I've read that people who live by the great barrier reef who have access to the most pristine water but still rarely perform water changes as in a well balanced reef aquarium It's just not required.

Is live rock limited as such or is my flow rate too low...?

I'm not interested in protein skimmers, algae scrubbers, vodka doesing or denitrification equipment including refugiums sumps or reverse osmosis.

Being less than 20 litres I'd rather perform a water change if my live rock isn't out performing the bio load.

My only interest here is to better understand other peoples experience with live rocks influence of nitrates..!

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Nitrate is reduced with in the nitrogen cycle via areas of low to near no oxygen called anaerobic, but are actually anoxic zones, anaerobic means a class of bacteria, these bacteria work well in your live rock, that is if its porus nature remain free of clogging rubbish/detritus.

So if you have “for instance” one kilo of live rock, then it will complete a small loads ammonia and nitrite to nitrate and reduce a little nitrate!

With the rest of the nitrate, that much live rock will only reduce “approximately only” one eighth of the produced nitrate, depending on your load!

Plus I hate live rock anyway, been there and not again!

The area that will complete the cycle “to nitrate”, is anywhere on any free of life surface, you will then need at least eight times that amount of live rock to easily get zero nitrate. It’s a slow process for water to penetrate your live rock while loosing it available oxygen content, or it is used up by the bacteria and protists on the exterior and a short distance in to the rock as it penetrates your rock so that the anaerobic bacteria that lives with in, protected from the harmful oxygen, can take out unavailable oxygen and leave only pure nitrogen which are the make up of nitrate.

Nothing in your aquarium will remain free of detritus for any length of time, so in this case you need to apply bio cubes, one type will take care of phos and titanium will take care of nitrate.

These are available at the stores, but with me one of club members just started handling dry goods at amazingly cheap prices.

Now that I am connecting all of my waters to my NWMSystem, even I have purchased a heap of other trendy gear I use-to-use back in the 80s and one or two newer types.

For a nano it is all up hill with phos and nitrate with out reactors as such, with my system it is impossible to find nitrate in a test, but you would not have the room for such a large external bio system.

It all boils down to an old term which is very apt, you can not have too much bio filtering, just to little!

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I swear after 12 months since first setup the live rock kept nitrates around 5-10 ppm but over the years thats just not the case.

I am very interested in the infomation already provided and will research more in depth to better understand your concepts.

I originally did have my concerns surrounding growth upon the exterior of live rock and the possible negative effects that would occur.

I will post a picture when I get around to it

I believe I have about 1kg of live rock in -20 litres but am willing to replace or clean up exsisting live rock if that infact in the root cause of my high nitrate levels

At first I was going to just add another pump to increase flow but I don't want to be lazy about it as this small aquarium is my learning tank before I convert a 80 gallon into a full Sps reef tank

So this pico tank is solely designed for pushing boundaries to better understand the limits of reefing.. As a prevention from future failures on a large scale.

I will return soon to further discuss any outstanding concerns or theories in the way of maximizing live rocks potential.

I greatly appreciate you attention of this simple concept and hope that live rock is a substantial key to the future success of Sps growth. Even though I'm currently under the strong impression that live rock alone may not meet the required processes that Sps demand in a way of nitrate reduction.

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My pico reef is only about 20 litres

Containing 2 clownfish, one bristle starfish and one frog spawn coral all of which are bullet proof from what I can tell.

I use one internal pump which creates tank flow and powers a spray bar for sufficient gas exchange.

I don't use a heater chiller skimmer sump or high watt lighting at this stage.

I wish only to firstly grasp an understanding in stability & boundaries of temperature bio-loads salinity nitrates phosphates calcium and trace elements before exploring high lighting and sensitive species.

I am a fan of the keep it simple stupid theory as a way of straight forward & inexpensive methods, as I am currently experimenting with rainwater as top-off with no ill effects so far after 11 months of use. Even though I realise the risks.

But that's exactly what this tank is for.. risks on the smallest of scales, potentially maximizing the effects.

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I wish only to firstly grasp an understanding in stability & boundaries of temperature

Just because you havent killed the livestock yet, doesnt mean the experiment is a success.

And it is certainly not preparing you for an sps stocked aquarium.

Dont get hooked up on just nitrates.

It may blind you to dangerous trends happening with other chemicals/minerals.

Much easier to keep up the water changes!

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Dam you Donny..!

I was on a roll in better understanding large scale tanks by using small scale measurements / experiments.

But since your going to contribute can you give a more broad explanation in the differences between nano & pico

I know it's late so when you're upto it I would greatly appreciate your version in the differences between the two.

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A pico is merely the smallest of the reef aquariums.

Where as a nano is a small aquarium.

For a 20L tank, you need a lot more tech to achieve the stability required for the more fussy inverts.

If you are happy with the current stocking, then stay the course....... well at the least add a heater for winter mornings.

If this tank is just training in prep for the larger one...... then sweet. But if you are getting attached and really want to push it to a more srs reef........

Temperature fluctuations resulting from such a small volume of water ~ a chiller and heater is needed.

Salinity fluctuations resulting from large surface areas of air-water-interface ~ an auto top up is needed.

Not wanting to sump or carbon dose ~ powerful lighting is required to promote algae growth.

Random mineral deficiency as a result of tiny volume + time between water changes ~ either dosing pumps or frequent partial water changes.

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The relationship between Nitrates & live rock is what stage I'm at..

I realize Sps is the holly grail and am years from it.. I know it, but your more then correct in saying this by no means succeeding but is a form of success even at the lowest level and I shouldn't have mentioned Sps, I just want to portrait the detail of measurement & understanding that I intend on gaining with the added mention of my goal.

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If you focus on having a nano, rather than a tiny full reef......... then all is good.

Keeping alive the frogspawn isnt too shabby a marker post to be guided by.

Nitrate reduction by liverock is decided by many things...........

Can we get a picture of the liverock in question, as its density decides a lot ~ volume for oxygen hating microbes to colonise.

As does the amount resting on substrate ~ will create oxygen poor environs even with shallow substrate bed.

Algae types colonising liverock ~ diatomeous, coraline, hair, slime and macro. All will absorb nitrates to grow.

Of course we need details trend data gathered from frequent nitrate tests to work out just how much excess nitrates is being produced, after the microbes/algae have had their fill.

Without data, you are just imagining/assuming.

IMHO if you are not going to increase lighting, then carbon dosing is your best bet.

Hang a little bag of nitra-guard in there. If you can hide it, it should reduce your water changes at least by half.

But I would still be doing them frequently.

The thing with a pico is....... its a way for the most experienced of reefers to show off.

Its not really so good as a learning tool. For that you want minimum 60 litres.

You just cant make mistakes in a 20L tank, without being punished.

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Mate sps is one of the easiest corals to keep with relatively easy care. The major issues come from them being very primitive invertebrates, that means they cannot handle what they were not born or evolved in, that being an aquarium and they evolved in the ocean! An aquarium is nothing like the ocean; the parts per million issues are staggeringly different and harmful to all aquarium life, to some degree. Sps cannot handle changes, especially sudden changes, of any kind! For instance, mine just had new lights put over them and they are now in shock and most of my reef life are loving them, but with my sps, I may loose some, but that’s just me not bothering to use the dimer function on the lights, but as I typed it is a sudden change of conditions. A small amount of water, if it changes I any way, then it changes quickly, no matter what. These types of events, “quick events”, shock the corals algae, for calcium-structured corals, their algae are their whole existence! If their symbiotic algae clades suffer, then the smaller polyp coral creature will suffer even more so.

As an example only, in my system the temp will take all day to go from 23c to 25c once the chiller is kicking butt, in yours it will quite possible happen with in one hour. When temps rise, your oxygen retreats in availability and impurities like nitrate and proteins and many more that were not much of an issue have now become toxic. Our tanks have sodium chloride in the water; the chloride component is extremely unstable and will appear as if it has separated from the sodium as temps rise, when that happens and your water isn’t spot on, you have what may act like actual chloride on its own in your water.

Edited by liquidg
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I was thinking of taking one rock out at a time (over many weeks/months) to dip in hydrochloric acid just to bring em' back to new.


I could just spray the exterior of rock with acid to clean off the bio material which I suspect is reducing nitrates penetrating deep into the rock, even tho osmotic pressure would eventually drag nitrates deep into the rock I still feel high pressure from high flow would assist much more efficiently therefore less growth would equal less resistance in allowing nitrates to reach denitrification bacteria.

pH was 8.4 now is 8.2 due to nitrates around 80 ppm

12 moths ago my nitrates never went above 10 ppm.. I believe was down to high flow rate within a small aquarium driving water deep into live rock.

amazing to say the least.

I can see that my flow rate has reduced to a degree from the amount of visible bottom glass in one corner where sand is being cleared away.

my live rock is from a store that was closing down and from what I can tell its large pieces of dead coral now completely integrated with life if all types some wanted some not, so any many ways this could be a good opportunity to try and remove some unwanted guests but Im not confident that's possible without a complete breakdown and fresh rebuild.

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Don’t do that to your rock, it is called cooking it and it is quite harmful to your reef life and is useless in the over all scheme of things!

You could remove that substrate, unless you siphon clean it each week or so or it is polluting your aquarium with nitrate and possibly sulphur as well. Those two fish are a large load on that type of rock with that water volume.

It would be so easy to make a reactor and chiller your self that are tiny and would not look ugly with a sock built in to the reactor and a pre filter on the pump for that tank.

One of our guys makes those tiny chillers and they are sold here in Aus now at a really cheap price as well

All done easy as!

Edited by liquidg
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I often use hydrochloric acid in a syringe to kill live rock pests once I remove the rock from the tank, rinse and quickly add back into the tank before it dries out, only killing the effected area. I guess if I were to treat the entire rock no beneficial bacteria would remain or anything else for that fact but that's kind of my intention to bring the rock back to new giving bacteria a fresh start with maximum flow, its an extreme and risky measure but I bet it would be effective over the long run to encourage denitrification as long as the exterior growth rate is slower then the internal bacteria growth rate, how much different would it be from adding more live rock and slowly remove existing live rock just because its becoming less efficient at removing nitrates.

I guess the sand isn't doing any good so I'll syphon it out, I use to have a clean up crew and syphon detritus weekly but noticed that it would dissolve if left to and would just become nitrates and phosphates. then after the denitrification process only phosphates would remain encouraging algae being a phosphate indicator given correct lighting of course.

I'm wiry of DIY denitrate reactors as they could easily cause hydrogen gas if not setup correctly, but I am interested in the mini chiller could you help me find the guy who makes them..?

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No mate, that’s old school and I use to make the silly things as well, plus they were not made properly any way and they can be, a reactor to house bio cubes +!

I am making one like my old one from the eighties, not a nitrate reactor, a three level reactor, but I had other things in it back then.

Now I am making it with first level bio cubes from the base up receiving the most oxygen, second level if I was using it, Phos killer, then a level of carbon, then good waters!

I am making it so I can take any section out at any time that want, some sections need to be changed or toped up at different time frames.

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No, you still need the surface area of the live rock to complete the nitrogen cycle to nitrate along with other functions and it does not have to be "live"!I always start tanks on sterilised base rock. You see from natural saltwater used at the start, comes all the varied bacteria for a healthy nitrogen cycle anyway.

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I use to live three levels up only by stairs, I would everyweek without fail rain hail or shine collect ocean water with a contraption I devised because during bad weather I could have easily been killed between huge swell and boulders.

I would filter the water by 50microns and use it.

collecting and performing 100% water changes gave me very simular results to minimal water changes and rainwater top off.

whats possible is the key to finding to balance and actual maintenance requirement given the species.

this frogspawn looked like this today and looked the same when I performed weekly WC and daily topoff siphoning cleaning and sterilising polishing pad.

to get the same results.

"the last shot was because I only just manually switched the light on"


I've noticed frogspawn can last weeks/months without food or light.

being it also gives off a chemical warfare Its really no good to me and I should get other softies.

meaning frogspawn and clownfish and bristle starfish and dancing shrimp are just not sensitive enough

as I do weekly top offs no water changing and very little polish pad cleaning. at this rate only phosphate and nitrate removal is required to function indefinitely, with that said only dosing, temperature control and lighting can complete my ability to attempt more sensitive species.

I only want to do as required, if that means 100% wc bi~weekly to keep Sps then so be it, but not 80gallons and not for fun.

I currently perform 50% wc in 80gallon cichlid tank every 3~4days so I am by no means lazy, I guess I just want to better understand whats possible.

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Bubbles are more stingers than chemical warfare.

I dont really want to argue any points with you Dane.

I shudder at the thought of only doing weekly top offs to replace evapouration in a 20L reef.

This whole thread reminds me of the Seinfield episode where they are seeing how far they can go in the car once the fuel tank reads 0.

Your prize for finding out how far you can push it........... is being stuck on the side of some random road broken down.

Your coral is big because it is hungry.

Its trying to maximize surface area to scavenge light.

I suspect its main food source though is likely fish and shrimp waste.

I salute your minimalist effort attitude........ but in your shoes I would just bite the bullet and buy a 20kg bucket of coral pro salt.

Theres easy a years worth of water changes in that, even if you do go nuts on them.

Maybe we can get a marine gurus take on it all [MENTION=9742]Nielsens Marine Mates[/MENTION]

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