Part 1: Water Changes During the Cycle

[seabass]

The dog woke me up. Poor guy is 13 and barks when he has to go outside.

[fewskillz]

The dog woke me up. Poor guy is 13 and barks when he has to go outside.

I know how that it is. My cat will get my attention whenever she wants fed, regardless of time of day or what I'm doing.

[seabass]

Some test closeups:

 

API ammonia test comparison (07/17/09):

 

Seachem nitrite test comparison (07/17/09):

 

Seachem nitrate test comparison (07/17/09):

[seabass]

In addition to the regular tests and the scheduled water change,

I included pH tests today:

• The pH of the water change water was 8.2

• The water in the test container (receiving water changes) had a pH of 8.1

• The water in the control container (with no water changes) had a pH of 8.0

[fewskillz]

Still following along. Good idea on the pH test.

[seabass]

There is a decent build up of food on the sand. I'll post a picture tomorrow. I didn't have my camera with me today, but it's getting pretty scummy in there. I'm hoping that as the bacteria population increases, it will be able to process all of the existing food.

 

Still following along.

 

Good idea on the pH test.

Thanks, I suspected low pH readings, but they were actually more in line than I thought they would be.

[seabass]

Test containers (prior to the addition of daily food pellets):

 

Test container closeup (control bucket):

 

API ammonia comparison:

 

Seachem testing:

[seabass]

It might be premature, but it appears as though ammonia has declined some. I had a difficult time color matching today, so I'll post some pics of the tests tomorrow.

[fewskillz]

Bout time that ammonia fell. Let's see how long it takes for the trites and trates to follow suit again.

[seabass]

API ammonia test:

 

30 minute Seachem ammonia test:

 

Seachem ammonia sensors:

 

Seachem nitrite test (top two):

 

Seachem nitrate test (bottom two):

 

Results to date:

[seabass]

I find it interesting that after eight partial water changes, the test container has a higher ammonia level and the same nitrite level as the control container. I assumed that ammonia production would be consistent between the two, and that water changes would remove a percentage of ammonia from the water in the test container (resulting in lower, not higher, ammonia levels).

 

However, it has occurred to me that ammonia production might still be consistent between the containers, but the control container is able to process ammonia into nitrite faster than the test container. This could mean that water changes are hampering the test container's ability to process the ammonia.

 

It appears that the control container is currently processing ammonia and nitrite faster than they are produced. If this continues, these values will soon become undetectable. On the other hand, the test container doesn't seem to have reached this point.

 

In addition, the nitrate level of the water in the control container also appears to be dropping. I believe that this is due to natural nitrate reduction (NNR). However, I'm not noticing any nitrogen gas coming from either of the sand beds.

[MikeTR]

Woohoo! So far it is consistent with my findings. I'm still betting your ammonia will be at least .5 on day 30 in the test container.

[Mr. Fosi]

Woohoo! So far it is consistent with my findings

 

Post graphs please. One of your guys should collect the data from the various "replicates" and write up a good summary. So far the results are interesting but they aren't firm enough for my taste.

 

A bit more time and some more data presentation are needed, but I know they are coming.

[seabass]

So far it is consistent with my findings.

Mike, I'd be willing to post (or link to) any details and data from this previously performed experiment. Just send me a message if you'd like.

 

One of your guys should collect the data from the various "replicates" and write up a good summary.

If anybody else has decided to duplicate this experiment, I'd be happy to post the details and your data (or at least provide a link to it). I realize that this experiment is time consuming and that there are costs associated with it, but we encourage anybody that's interested, to duplicate it (or even a variant of it - like with larger water changes, or using just one large measured amount of ammonium instead of adding food pellets everyday).

 

So far the results are interesting but they aren't firm enough for my taste.

I agree, the data from my experiment is just getting interesting. Plus, I can't help thinking that some other variable is affecting the results.

For example, water changes could be causing greater disturbance of the left over food pellets, and thereby increasing the rate of ammonification in the test container.

I'll post pictures of the containers later today so everyone can see what they currently look like.

[HydorMan]

However, it has occurred to me that ammonia production might still be consistent between the containers, but the control container is able to process ammonia into nitrite faster than the test container. This could mean that water changes are hampering the test container's ability to process the ammonia.

 

I agree with this. The thing to remember is that the conversion of Ammonia to Nitrtate is dictated by the number of bacteria in the system. This result suggests that the number of bacteria in the water column is critical to the ammonia reduction rate. Water changes remove these free floating organisms. Another possibility is that inorder for the the bacteria to ramp up to maximum reduction rates, their has to be a critical level of ammonia in the system. If this level is never reached the population of bacteria never grows and works at its optimal rate.

 

 

 

You probably would not see active gassing from the sand bed if nitrates are being reduced to nitrogen gas. I do agree that the nitrate reduction is probably due to bacteria in the deep sand bed of the bucket. The experiment has been running long enough to develope and anaerobic zone in the sand to facilitate nitrate reduction.

[MikeTR]

I don't have any experimental data, only observational and none is recorded. My experience comes from setting up a QT to cure ich. It was run with barebottom and a HOB filter that I seeded with 50% of the water & filter floss from my display tank. I was doing 50%-75% water exchanges daily or every other day to keep the ammonia under 1 and the nitrites under 5. I figured if the levels got much higher the fish would die. I continued this grueling process for 8 weeks. The cycle finally finished only after I had to go away on business for a week and thus couldn't change the water. I figured the fish would be dead when I got back, but I was pleasantly surprised they survived and the ammonia and nitrites both read 0.

[seabass]

 

 

 

 

 

Results to date (so you don't have to refer to previous pages):

[seabass]

I don't have any experimental data, only observational and none is recorded. My experience comes from setting up a QT to cure ich. It was run with barebottom and a HOB filter that I seeded with 50% of the water & filter floss from my display tank. I was doing 50%-75% water exchanges daily or every other day to keep the ammonia under 1 and the nitrites under 5. I figured if the levels got much higher the fish would die. I continued this grueling process for 8 weeks. The cycle finally finished only after I had to go away on business for a week and thus couldn't change the water. I figured the fish would be dead when I got back, but I was pleasantly surprised they survived and the ammonia and nitrites both read 0.

Thanks Mike, very interesting. I hope that I get some clear data by day 28, as I will be going out of town and won't be able to extend the experiment.

[Mr. Fosi]

Interesting data so far.

[seabass]

Interesting data so far.

And unexpected (at least by me).

 

Although I'm at a loss to explain it (with just over a week to go), it seems apparent that water changes do affect the duration of the cycle. It makes me wonder if water changes are disturbing the pile of food enough to alter the results; however, MikeTR's observations suggest that this isn't the case.

 

Traditional explanations state that bacteria reside mainly on hard surfaces (like the substrate and live rock), and that bacteria in the water column are relatively insignificant by comparison. Therefore a 25% reduction in populations, that reside in the water column, shouldn't cause a significant effect in the overall bacteria populations.

 

I'm speculating that effect of water changes on the cycle has more to do with changes in bacteria populations than with the dilution of NH₄⁺, NO₂^-, and NO₃^-. However, since we are only measuring the byproducts of each phase of the cycle (and not the actual bacteria populations), there is no evidence that this is actually the case.

 

So do water changes improve the rate of ammonification or do they hamper the rate of nitrification? With the focus on the duration of the cycle, the answer might not be relevant. And although I'm looking forward to the end of this experiment, I almost want to run a variant of it to answer this question.

[Mr. Fosi]

Well, when you think about the surface area in your typical LR-filled tank, these test buckets are lacking. If it is a bacterial export thing (which I still doubt), it may be more noticeable in these tests because of the relatively low amount of surface area available for colonization.

[seabass]

Well, when you think about the surface area in your typical LR-filled tank, these test buckets are lacking. If it is a bacterial export thing (which I still doubt), it may be more noticeable in these tests because of the relatively low amount of surface area available for colonization.

You could be right about bacterial export not being the answer (the post was the result of a 3 a.m. brainstorming session). However, I don't think that surface area is an issue either.

 

According to CaribSea, aragonite sand contains 20,000 square inches of surface area per cubic inch of sand, and the surface area of Ocean Direct substrate is 0.728m²/g (3,569 ft²/lb), measured by the BET N2 method. In addition, each container has 20 lbs of sand, while a typical nano reef of this size might only have 5 to 7 lbs of LR plus another 5 lbs of sand.

[Mr. Fosi]

A good argument but sand surface area =/= LR surface area.

 

It seems as though a lot of the surface area of the sand is interior, whereas the surface area of LR is exterior. This has implications for O2 and DOC availability, which both can affect the establishment of hetertophic bacteria.

[seabass]

It's an interesting thought, as MikeTR's quarantine tank had even less surface area. Plus, I do agree that LR and LS have different properties. But as we discussed in the design thread, it would be difficult to establish if the surface area and density (plus organic matter) of the LR would be similar between the two containers.

 

Therefore, for the purpose of this experiment, we're stuck with this restriction. However, I don't think that the sand is changing the overall trend that we'd see if cycling with LR. And while I'm not sure if I completely buy into the idea, I'll concede that the lack of LR could be affecting the results. Which, I believe, was your original point.

[seabass]

Day 21:

It's the end of the 3rd week, and today was the 10th one gallon water change for the test container. I couldn't detect ammonia in the control container's water with the API test; however, I was able to detect a trace amount using Seachem's test.

I find the API test kit to be easier to read at or above 0.25 mg/L, but the Seachem test kit is more sensitive at lower levels.

 

Ammonia (NH

₄

⁺

), test container: 1 mg/L

Ammonia (NH

₄

⁺

), control container: 0.1 mg/L

Nitrite (NO

₂

^-

), test container: 1 mg/L

Nitrite (NO

₂

^-

), control container: 0.5 mg/L

Nitrate (NO

₃

^-

), test container: 2 mg/L

Nitrate (NO

₃

^-

), control container: 5 mg/L