I'm fertilizing my tank

[Ink]

I am a seasoned reefer. I started to be into this hobby 17 years ago.
In my last 7 years, I feel I have continuosly fought against slow grow and undetectable inorganics.
My tanks were setup as most of modern tanks. Live rocks, skimmer, medium-strong light. Good water movement.
I kept a normal fish population (not too small in my opininon): in my previous 130 gal tank, I had 4 tangs and 20 small fishes.

In my previous tank and in the actual one, that is 1 year old, I've epxeimented addition of inorganics to overcome the problem.
I started with nitrate (NaNO3). Then I tried adding phosphate (NaH2PO4). Then I tried ammonia (NH4HCO3). Then I combined the last two.

Single elements addition was a disaster. At that time I couldn't figure out why in the first days adding the solution, that inorganic remained undetectable and corals immediately started to thrive. After some time, both progressively increasing the dose of the solution, both keeping the same small initial dose, my corals started to worsen and that inorganic began to rise. I quickly reduced and then stop adding the solution, but that inorganic remained at the reached level. Only after some weeks and water change, situation came back to the beginning.

After various attempts, I started realizing why this was happening and didn't worked as expected.
My hypothesis was I began adding a deficient element. Corals get benefit from that in the first time. Because carbon was available, adding the deficient element allowed to consume the other element (either nitrogen or phosphorous), until it started to lack. Once the other element get deficient, corals start to worsen again and the element I'm adding can't be consumed any more and begin to accumulate in the water.

So I tried adding both element together, separately. I wanted to balance the consume in the water of both and add the right dose to keep both them detectable, avoiding limitation of one.
After some time, I found a constant dose for both the element (NH4 and PO4) and corals finally started to improve.
I observed the ratio between the two product was matching the redfield ratio (N=16).
So I prepared a solution containing both the elements with that ratio (63g HCO3NH4 and 6g NaH2PO4 into 500ml RO/DI water) and I now am adding it continuosly (5ml per hour in a 320 gal tank).
This way I can keep my PO4 at 0,05ppm and 1ppm NO3 and my corals are continuosly improving, both colors and growth.

Luca

 

[Ontheway]

Interesting, can you please provide more info, like, what was the number for nitrate and phos before treatment and how long you are applying these chemicals together?

 

[Ink]

Ontheway,
without adding any solution, my tank has NO3 undetectable and PO4 among 0,00 and 0,02ppm on Hanna photometer (multiple triton tests detect PO4 always <0,018ppm).

For the sake of correctness, in the last days I found nitrate increasing more than phosphate. So I started adding a PO4-only solution.

Today I have NO3 5ppm and PO4 0,09ppm. I find incredible how my colors are just a little too dark for my taste (and I'm very demanding) and corals are so healthy.
These values are however too much IMO, so I will let them reduce. My target is PO4 0,04ppm and NO3 0,2-0,5ppm.

I think using 2 separate solutions, one for ammonia and one for phosphate, is the easiest way. I think it is important to use very diluted solution, so to add them every hour via dosometric pump. This allow us to have a very fine regulation, avoiding sudden changes and equally important to be able to make testing in every moment of the day, because the concentration into the water is really constant. If we instead add the solution once or twice a day, testing must be related to the time of the day, and it would be very hard to take a decision about dosage.

Please also look at this fresh new article:
http://www.advancedaquarist.com/blo...phorus-and-zooplankton-key-to-coral-nutrition
It seems to appear at the right moment.

Luca

 

[Ink]

For a practical purpose, I actually was adding 5ml/h of a 10 liter solution containing 63g NH4HCO3 and 6g NaH2PO4 and 3ml/h of a 10 liter solution containing 3g NaH2PO4.
With the values I detected today, I simply reduce the first dose to 3ml/h and the second one to 2ml/h.
After 72h I will retest and decide any eventual other change. Very easy.
I am not afraid to find further increase of the values. First because it will not cause any harm. Second because I know that suspending (better reducing) the addition will cause the inorganics to reduce, until both elements are available (carbon is not limiting into my tank).

Luca

 

[sculpin2]

In related news...

http://www.advancedaquarist.com/blog/balance-of-nitrogen-phosphorus-and-zooplankton-key-to-coral-nutrition

 

[Ink]

It would be useful to have access to the original article. The AAOL page doesn't provide enough details to evaluate the impact of the single parts. It just let us guess the article is on the same way of my experience.

Luca

 

[sculpin2]

It does sound like that. Perhaps you should try a third variable, with an organic carbon source (which I would guess the zooplankton is equivalent to)?

 

[Ink]

Sculpin, I don't think so.
The fact in my tank nitrate and phosphate spontaneously reduce to undetectable makes me think I have no carbon limitation, but an excess of it.
So adding organic carbon I think It would nullify my effort to raise N and P adding ammonia and phosphate. I also think zooplankton can't be assimilated to organic carbon. I rather think zooplankton is organic nitrogen and phosphorous and it consumes organic carbon.

Luca

 

[Timfish]

I think you will enjoy Forest Rohwer's "Coral Reefs in the Microbial Seas" He talks about the research showing the importance of phosphates and nitrogen to corals reefs and the negative impact of Dissolved Organic Carbon has on the health of a reef. Here's some additional papers you might find interesting:

Ammonia uptake by symbiotic and aposymbiotic corals
http://www.ingentaconnect.com/content/umrsmas/bullmar/1979/00000029/00000004/art00011

High Phosphate uptake requirments of the coral Stylophora pistillata
http://jeb.biologists.org/content/214/16/2749.full

 

[Ink]

Thank You Timfish. I'll read the two article ASAP.

I hope I will find the book in Italy too. I'll look for it immediately.

Here another link on the theme:
http://www.researchgate.net/publica...coral_reefs_the_cryptic_carbon_shunt_revealed

Luca

 

[cham]

Love your write up, I have a similar issue of too clean of a tank. I had let my tank go fish only for a couple of years and my N03 was very high. After restarting as an SPS reef my skimmer went nuts until my N03 went to zero (took about 2 weeks) and since then my skimmer stopped skimming and P04 has remained elevated.

Yesterday I started dosing Kn03 and I hope to just dose enough of it to keep my P04 low, but not at zero. Addition of P04 a lower levels should be easily done by multiple pellet feedings daily.

 

[Ink]

Cham, it's difficult to predict your tank response. You have to monitor it. Maybe Your're right, maybe your PO4 will quickly lower to undetectable or also to a level You think it's good low, but it's too low for Your tank. That's what happened to me. My photometer showed 0,02ppm PO4, but triton said <0,009. So when things will get steady, give a try adding some pure phosphate.

Timfish, I'm reading the book You advised me. Really mind opening.
I've just added 4 tangs today.
I think keeping enough inorganics to allow algae to grow (probably barely detectable by tests), and get controlled by fishes, so algae do not expand but are constantly mowed, it is the key to success. Skimmer is the device that control organic carbon excess.
A tank without algae grow (I mean also algae film on rocks) and with a skimmer that produce small skimmate and is unstable, means lack of nutrients. That's what I've had for several years.

If You know any other book as the one You advised, I would be very happy to read it. Thanks.

Luca

 

[DiscusHeckel]

This method is already available commercially and marketed by Tropic Marin (refer to Tropic Marin NP bacto balance). I use it in my tank and it works.

 

[norskfisk]

You could also consider not just adding N and P, but a complete nutrient solution like modified F/2 algae growth medium. It also contains iron, 3 vitamins, zink, manganese, copper, cobalt, molybdenium. Some modifications have iodine and others.

How about feeding the corals more? That's the "natural" approach ;-)

 

[DiscusHeckel]

You could also consider not just adding N and P, but a complete nutrient solution like modified F/2 algae growth medium. It also contains iron, 3 vitamins, zink, manganese, copper, cobalt, molybdenium. Some modifications have iodine and others.

How about feeding the corals more? That's the "natural" approach ;-)

Tropic Marin also has K+ elements (barium, boron, chrome, cobalt, iron, copper, manganese, nickel, strontium and zinc) and A- elements (bromine, fluorine, iodine, lithium, vanadium, molybdenum and selenium) that are supposed to be used in conjunction with NP bacto balance. These three products offer a complete solution to nutrient management, coral growth and coloration.

 

[00101]

Tropic Marin also has K+ elements (barium, boron, chrome, cobalt, iron, copper, manganese, nickel, strontium and zinc) and A- elements (bromine, fluorine, iodine, lithium, vanadium, molybdenum and selenium) that are supposed to be used in conjunction with NP bacto balance. These three products offer a complete solution to nutrient management, coral growth and coloration.

I'd be wary of dosing a bunch of things that you don't have any way of testing for.

 

[DiscusHeckel]

Sure, but I have been doing it since last February. My tank is getting better and better. I can test for nitrates, phosphates, alk, ca, mg, potassium and for the rest that I cannot test for I observe my corals daily and use them as my bio indicators.

 

[Subsea]

Cham, it's difficult to predict your tank response. You have to monitor it. Maybe Your're right, maybe your PO4 will quickly lower to undetectable or also to a level You think it's good low, but it's too low for Your tank. That's what happened to me. My photometer showed 0,02ppm PO4, but triton said <0,009. So when things will get steady, give a try adding some pure phosphate.

Timfish, I'm reading the book You advised me. Really mind opening.
I've just added 4 tangs today.
I think keeping enough inorganics to allow algae to grow (probably barely detectable by tests), and get controlled by fishes, so algae do not expand but are constantly mowed, it is the key to success. Skimmer is the device that control organic carbon excess.
A tank without algae grow (I mean also algae film on rocks) and with a skimmer that produce small skimmate and is unstable, means lack of nutrients. That's what I've had for several years.

If You know any other book as the one You advised, I would be very happy to read it. Thanks.

Luca

Luca,
I got my copy of that book from Timfish. Instead of using skimmer for organic carbon, have you considered using granulated activated carbon. There is peer reviewed research articles in Advanced Aquaria on this subject that is connected to carbon dosing using skimmers as nutrient export. Timfish and I are both skimmerless with tanks >20 years old.

 

[Tigé21v]

Ink, what made you decide to dose ammonia instead of nitrate? Is there a gain from allowing for the complete nitrogen cycle?

 

[Ink]

Sorry for so late reply.

Subsea, my current opinion is that to have best colors and health on SPS, I need a system very poor in organic nutrients. I currently run two skimmers, biopellet, activated carbon and dose acetic acid. I think these factors mainly acts on organic nutrients because of two facts. My tank never changed nitrate and phosphate level (0,2ppm and 0,015ppm respectively) despite I progressively added and increased BP (1,5 liter on a 1200 liter tank), a second skimmer, doubled the dose of activated carbon and add acetic acid (8 drops of pure acetic acid).
A friend's tank removed the skimmer about 8 months ago. His inorganics level didn't changed too (same as mine), but tank is a mess. Water is heavily green coloured and rocks and corals are very dark, with poor growth. It seems like if light can't penetrate the water.

For this reason I think it is good to have a system that quickly removes organic and I'm currently adding boluses of inorganics (nitrate and phosphate) every few days. I still have to understand if it is better to add larger doses on longer period, or smaller doses more frequently.

I think the balance between light and fish population determines the level of inorganics in the water. In the past I verified more than one times that photoperiod duration heavily change inorganics level (more light lower inorganics).

I don't think it is a good idea to add other minerals too (like iron). As said, too hard to measure.
I have had until few weeks ago a problem with green hairy algae. I couldn't explain why they where there perfectly thriving, despite optimal nutrients level in my tank. Triton test told me zero iron, but I recently discovered the pump of my BK had a break inside and was full of rust.
I substituted the pump and algae are finally receding (actually about 70% gone away).

Tigè21v,
there are multiple demonstrations that ammonia is taken up faster than nitrate from zooxanthellae (they need to produce an enzyme to take up nitrate). Moreover it has been shown that corals too can directly absorb ammonia, but they can't nitrate.
Anyway I'm actually experimenting nitrate boluses, mainly because I'm afraid adding a large dose of ammonia in one shot can cause toxicity (I mean 1ppm in one shot).
If I'll found better to add small doses more frequently (I'm sure it is safe until 0,3ppm in one shot), I'll probably come back to ammonia. I have many experiments on my list.

Luca