Nitrogen Dosing

[garyl]

I have a 14 month old, 140 gal mixed reef with a refugium and a little bit of chaeto growing in it - not really that much, a bunch of chaeto wisps really.

While I never had high nitrates and phosphates (maybe 15 N and .1 P) I decided to try NOPox and see what happened.

I used a very small dosage of 4ml/day on a doser, knowing that is way lower than what Red Sea recommended.

What I found was that after about 3 months, my nitrates were down to about 2 and my phosphates are somewhere in the range of .06.

I backed off my dosage to 3ml/day, but my nitrates are staying down about 2 - this is a little worrying to me, because I know that the test kits are not super accurate - (using Hanna checkers).

In a mixed reef, I would be very happy with Nitrates of around 6 and phosphates of around .06.

BTW, I have a well-stocked tank, feed quite liberally, and do a dosed 2gal water change per day.

So, I have a couple of questions.

1. How are my nitrates going so low with such a low dose of NOPox? Is it the NOPox that is doing the reduction or some other reaction that is taking place naturally? Can I back off the dosage even more and expect to see a rise or are the bacteria feeding off some other carbon source?

2. At what point should I think about dosing Nitrogen? (TBH, I never dreamed I would ever say or think that.)

3. If I do start to dose Nitrates, do I continue with the NOPox? Seems like a bit of a push me pull you type of environment...

Thanks for any help.

Gary

 

[Chris.Reef]

Was there a reason that you started dosing NOpox In the first place with 15 nitrate and .1 phosphate? Was there an issue with coral growth? 15 and .1 are good numbers to have in a reef tank

 

[afboundguy]

Was there a reason that you started dosing NOpox In the first place with 15 nitrate and .1 phosphate? Was there an issue with coral growth? 15 and .1 are good numbers to have in a reef tank

That was my first thought as well. Did you start dosing to get better chaeto growth or for another reason? I know plenty of tanks and have had a few tanks without a refugium that did very well.

 

[garyl]

TBH, I had a conversation with someone how we can now really "control" nitrates with carbon dosing as opposed to just try and use macro algae in a sump to reduce it without any mechanism of knowing exactly how much will be reduced.

I have recently returned to the hobby and Nitrates and phosphates were always the giant bogymen lurking in your tank slowly killing corals. I was interested to see if there really was a way to reduce nitrates in a measured way. I guess I expected to see that carbon dosing would help me "dial" in the levels I was looking for.

What I wasn't expecting to see, was that while it really seems to work, "dialing" it in is not quite as simple as one would think. Now I'm wondering if it really is a manageable solution or closer to the macro algae solution.

I have been doing some more reading today on the subject and on Reef to Reef many people say they only use a maintenance does of 1 ml/day and seem to be quite happy with the results. Seems to me, that is so small of a dose, that there must be some other mechanism that I have released that I don't understand.

 

[afboundguy]

Makes sense now. I don't think the 15 and 0.1 are big numbers at all and I wouldn't be worried about it as long as the tank looks good and everything is growing.

I remember when I first started it was all about zero nitrate and as close to zero phosphates as well and I had decent growth. Now it seems like detectable nitrate and phosphate is better but I've had good results both ways.

I would subscribe to the notion of if it ain't broke don't fix it especially with those numbers.