An experiment in nitrate reduction

[dleute]

A few things fyi:

I agree the ammonia likely caused the nitrate via chemoautotrophic ammonia oxidizing bacterial activity converting it to both to nitrite and then nitrate.

Denitrication via the normal cycle requires anaerobic ( low oxygen availability) activity , usually occurring in substrate or pores of live rock where oxygen rich water is very limited given low flow in these areas. Obviously ,this requires adequate surface areas exposed to hypoxic (low to no oxygen) bearing water. It can take time for the denitrifying bacteria to establish themselves in these areas where they reduce the nitrate (NO3) to N by taking oxygen from it when free oxygen is unavailable leaving some of the remaining N to bind with N forming N2 ,nitrogen gas which bubbles out of the tank retunign the nitrogen to the atmosphere . More porous surface area can help increase the anerobic activity.

Carbon dosing feeds heterotrophic bacteria which primarily take the N (nitrogen ) from ammonia directly in a one step process without adding nitrate.In essence reducing the amount of new nitrate in the system. They also use some nitrate, phosphate and other elements) . It can take months for nitrate present at the start of carbon dosing to be reduced. They can also reduce the ammonia oxidizing bacteria in play by outcompeting them for ammonia. The 40ml 5% acetic acid vinegar dose for ca. 100gallons is moderate ,IMO.

I'm glad to hear it's moderate. I was shooting for that. I didn't want to over or under dose.

I decided to add fish yesterday since tank parameters have been staying solidly within range even with the experiment for several weeks. So that's new. Obviously, no more ammonia dosing. I chose this for a few reasons:

1) I wanted to move to a natural cycle instead of an overstimulated artificial cycle created with ammonia.
2) I wanted to actually feed something with the food I was using.
3) After all I've read, I felt like the fish would not be at risk beyond normal new cycle tanks.

So now there are two small royal grammas and a dot dash wrasse in the tank. Their names are Houdini, Purple (my almost 3 year old son named this one) and Abbey respectively. As well as 5 nassarius snails to clean up the food a bit. They are all eating and active (yay!)

Carbon dosing essentially helps in skipping the nitrification and denitrification process. So really, my last ammonia doses may have been handled more by carbon dosing than the full nitrification and denitrification processes. I was wondering why it seemed to process ammonia significantly faster (hours instead of most of the night).

Based on what you just said, that would indicate that the process of removing nitrates naturally may be responsible for some or even most of the existing nitrate reduction? Basically marine pure (and 50lbs pukani) is doing what it said it can do? (I have an 8x4 in the drain section of the sump, hopefully slow flow enough, an 8x1 in the overflow and an 8x1 split into two between sump baffles more for nitrification in fast flow)

I have only been dosing vinegar for a few weeks. So there shouldn't be significant nitrate reduction from that method (is that true even if there are bacteria blooms? it seems like that much bacteria should be pulling out nitrate when collected or filtered out?) Indicating that denitrification has started happening in the marine pure? (I don't think my 2 inches of aragonite live coral sand can do denitrification)

I also got my ro/di and saltwater slightly automated so I have 30% saltwater immediately available with another 30% ro/di immediately available to make into salt in an emergency. (could do that once or twice a day if I absolutely had to).

If I see nitrates rise instead of continue to fall, I'll start changing water ASAP.

--Derrek

 

[dleute]

The most important thing that has happened is my son renamed Purple to Corduroy. Or maybe Cookie Monster. He's still not sure.

I also bought the API nitrate kit. I don't love it. I was hoping the colors would work better for me. The salifert kit seems to be the best for me so far. I also cleaned up more bacteria bloom (mostly on glass). I'm also reducing feeding to only what the fish need. Still researching what is enough food, but I imagine if each fish eats a few pellets per feeding, twice a day, they are not going to starve.

They look happy and healthy. I will be posting pictures of them in the build thread in the not too distant future.

--Derrek

 

[dleute]

Lost a fish.

Lost a fish.

I haven't updated this thread because one of my fish started breathing heavy a week ago. It was Abbey my dot-dash wrasse. Tracking nitrates specifically became secondary to trying to identify the problem and help the fish. At first I didn't know whether it was unusual or not. It just didn't look like the royal grammas breathing. But she was still eating and being active. The heavy breathing was first noticed a few days after she was put in the tank.

A few days ago she started swimming differently. This is when I finally was convinced she was sick. Unfortunately, I likely took action too late (if anything could save her). I started doing large water changes.

Today Abbey died. I stupidly discarded the body before inspecting her gills.

In fact, she jumped out of the tank as I was finishing up the water change (lid was even on, but my lid doesn't cover every inch unfortunately). I got her back in (was standing right there), but she clearly couldn't take it.

I think the royal grammas knew as they started hiding today while Abbey was swimming funny. Normally they flank her and happily swim about when she is up. Now I can't find them either. They also don't like when flow in the tank is high. I turned it down to encourage them to come out.

I hope they are ok.

Tank paramaters:

Nitrates: still around 25-30. Haven't done the diluted reading in a while to get a better result.
Ammonia: 0 (from seneye)
Salinity: ~1.025 (depending on if you believe Apex or Digital Refractometer)

I haven't tested phosphate in the last week or so, but it was 0.02 or less.

I did just have a diatom bloom. I also blew off my rocks and caught most of it in the filter sock. Bacteria blooms seem to be over.

Anything else I should check? I want to make sure I'm giving Corduroy and Houdini the best chance possible.

--Derrek

 

[bertoni]

Those number are all fine for fish. I probably would check the temperature, in case the heater has died, but that's fairly rare.

 

[dleute]

Those number are all fine for fish. I probably would check the temperature, in case the heater has died, but that's fairly rare.

I've been running my temp at 82. Just reduced to target 80 as I ready about oxygen in temperature.

It was always in the 80-83 range (83 spikes happen from time to time. still can't figure out why also one of the reasons I reduced the target temp). Both the low and high end was rare spikes like during water changes or other maintenance.

I don't think that temp should be a death sentence for a wrasse. But if it is, .

--Derrek

 

[bertoni]

No, that temperature range is all fine. The fish won't care. Corals are much more sensitive.

 

[dleute]

No, that temperature range is all fine. The fish won't care. Corals are much more sensitive.

Yeah, that's why I went for 82. I've read that that is a good coral temp and fish will adjust.

No corals or anything else in the tank yet. Just the fish.