How adding KNO3 saved my tank, and why nitrates are not always evil

[R_MC]

Hi All,

 

In the last few months I've had a sort of revelation. I know that this is well known to some, but not all as I had read plenty and still believed that in order to maintain good water for SPS coral you wanted nitrates and phosphates as low as possible.

 

As a very brief backstory, I have had some ups and downs with reef keeping:

 

I started with a 45G tank and T5's and had a bit of success, I didn't measure anything except salinity, didn't do my water changes, and dosed two part hap hazardly. I did feed very lightly, had a small skimmer, and grew cheato in a sump:

Photo @ 5 months or so

 

This tank was up for 7 months or so before I changed apartments and picked up a 93g corner tank. This tank had a better skimmer and a more extensive refugium. I fed heavily and kept up alk/ca with kalk but never really tested. This tank had a lot of highs and lows that I never understood (because I was not tracking nutrients / water chemistry). It was mostly a softy tank and so it was pretty easy to keep with in hood leds.

 

Photo at 1.5 years

 

Again I moved...Setting up and breaking down a 93g tank for 2 years of reefing took its toll and I almost wanted out. The disease was too strong though and I picked up a very used 30g shallow tank. I am slowly in the process of converting this tank to SPS only and with that goal in mind I initially set out to drop nutrients as low as possible.

 

Some of the steps I took to keep N and P bottomed out were: GFO, Dosing 1ml of vinegar / gal, Kalk, very heavy skimming. I wasn't measuring and my coral was pretty pale.

 

Here's an example of what an ORA blue birdsnest looked like.

 

And a top down shot - the small bright sps frags were just added and quickly paled out.

 

I thought it must be my lighting so i lowered my lighting but noticed tissue recession and no increase in coloration... so I brought my lights back up and tested everything... Alk was high (11) so I dropped it to 7, I noticed this seemed to help with the tissue recession but that the coloration just wasn't there. So I bought a nitrate and phosphate kit and took some readings. The readings showed both bottomed out at 0.00 and 0.00. I fed VERY heavily but could not increase the nitrate level at all.

 

Enter KNO3 - sodium nitrate. I figured that I would try raising my nitrate very directly to 2ppm using KNO3. It worked. I've kept my nitrates between 2 and 6 ppm (phosphate still almost 0) for the last 2 weeks and I've noticed some great changes to my coral. Here is a shot of the same birdsnest after just one week of raised N levels:

 

 

Since adding KNO3 my coraline growth has taken off. Everything has taken on a richer more saturated color. My LPS which was previously retracted has once again extended more fully.

 

I feel like I have just begun to understand why my previous tank would go through periods of looking pale and sickly and periods of looking rich and full. I understand that some like the pale / pastel look, however I like rich saturated healthy looking coral.

 

For me, understanding that nitrate should be treated more like Alkilinity / CA / Salinity than a "waste" chemical that needs to be removed was a revelation.

[OCNcheffy]

I'm curious if adding amino acids such as acropower or reef energy would have solved your coloration issue.. They say amino acids for sps work the best with an ULNS tank, which yours pretty much was.

[Nano sapiens]

Corals have multiple feeding modes. However, if organic (feeding) and inorganic (Ammonia/NO3/PO4) are very low they will not thrive.

 

Feeding is preferencial and is why coarls can do well in the natural environment with typically very low nutrient water. However, in our tanks, we tend to provide a higher nutrient enriched environment than in nature, but less food items.

 

Bottom line, corals will use any nutrient source that they can get a hold of and that's what you are seeing here.

[ReviloM]

One typo in your original post - KNO3 is potassium nitrate and not Sodium Nitrate