Designing an experiment: WC's during the cycle

[seabass]

Why are you using live sand and not sterile? This will be an uncontrolled variable that confounds any results you get.

I chose live sand to introduce bacteria. The sand for each tank would be from the same bag and mixed. I feel that this would provide a consistent bio-filter for each tank. Dry sand might not be any more consistent. A synthetic media (like bio-balls) might be the only filter which can be better controlled.

 

"One shrimp" hardly seems like a controlled variable as well. I imagine that if you placed 10 shrimp in 10 5g buckets, you would have very different NH3 levels in each one after one week. I think ammonium chloride would be the way to go here as it will give you a much more precise result.

I'm open to a more measurable source of ammonia. Instead of shrimp, we could extend our use of food pellets. Possibly starting out with 24 food pellets (instead of the shrimp), and introducing an additional number of pellets daily.

 

What are you testing the NH3/NO2/NO3 with? What is the threshold of each at which you declare the bucket has "cycled"?

Our current plan is to use a Seachem MultiTest Ammonia test kit. Since this experiment is focusing on ammonia as the primary dependent variable, it will continue until we can no longer detect it in either tank (although we will probably extend the test until we can no longer detect nitrite as well).

 

Do you plan on keeping the control and test bucket "double blinded"?

No, I would be performing my own tests, while being aware of which bucket is receiving water changes.

 

I don't mean to discourage you as it is an interesting and worthwhile endeavor, but this kind of thing needs to be rigorously replicated for any result to be meaningful.

No problem, you've presented some helpful things to consider. This was originally going to be an informal experiment. However, I still chose the materials in an attempt to eliminate many and minimize other dependent variables. The only independent variable will be a pre-determined water change schedule for the test tank. We realize that the closer we get to real world conditions, the more variables we introduce.

 

It will not be practical for me to perform this test in an strictly controlled environment. The best that I can do is provide the same variances to both the test and the control tank. While bio-balls and ammonium chloride might prove to be a more reliable test, it doesn't 'feel' as natural (although I'm still open to changing the test to this, or even something else).

[Mr. Fosi]

I'm open to a more measurable source of ammonia. Instead of shrimp, we could extend our use of food pellets. Possibly starting out with 24 food pellets (instead of the shrimp), and introducing an additional number of pellets daily.

 

Then seriously consider a non-food form of NH3. Since you are only really concerned with what happened vis a vis the NH3 and NO2, you should add a known quantity of NH3 at the start.

 

The best you will get with using food or shrimp (after weighing and crunching numbers) is an estimate of how much N you added and that will be confounded by the facts that: 1) reduction of protein-based N is inefficient, 2) much of the N liberated and reduced actually ends up as microbial biomass and not in the water and 3) your test kits aren't very sensitive.

 

IMO, adding a known, quantified amount of N is the way to go and testing for NH3/NO2/NO3 during the course of the experiment is a good idea but you may learn as much from the endpoint (when NH3/NO2 become undetectable) than you do from the intermediate data points.

 

This experiment won't be perfect (none ever are ) but if you make your goals more modest, you will have more believable/applicable results. This means that you might have to give up some of your "let's make it like the real world" in order to actually see differences.

[seabass]

Thanks Mr. Fosi, I really do appreciate the suggestion. What is the best source of ammonia, where do I get it, and will it be pure enough that we can use the sand (if we go that route) in a reef tank after the experiment?

 

Maybe we forget about using live sand in favor of a synthetic media?

 

If we use synthetic media + ammonium, do we bother adding any bacteria? Even a cup of water from an existing tank?

 

Do you propose that the revised experiment should look more like this:

• we fill both tanks with saltwater

• add synthetic bio-media

• add ammonium

then:

• top off tanks daily

• test ammonia, nitrite, and nitrate every day

• perform water changes on the test tank every other day

[Mr. Fosi]

What is the best source of ammonia, where do I get it, and will it be pure enough that we can use the sand (if we go that route) in a reef tank after the experiment?

 

Option 1 - Ammonium Carbonate, $3

Option 2 - Ammonium Hydroxide, $17

 

One is food-grade, the other is reagent grade (both pure enough). Both can be purchased from Post Apple Scientific

 

IMO, the NH4OH is better because it is more stable (doesn't adsorb CO2 and water as quickly) and it doesn't have carbonate in it.

 

I would stick with the LS, IMO. There are reasons to go with synthetic media but that is one step too far away from reality, IMO. Perhaps wombat can support or refute this.

[wombat]

Thanks Mr. Fosi, I really do appreciate the suggestion. What is the best source of ammonia, where do I get it, and will it be pure enough that we can use the sand (if we go that route) in a reef tank after the experiment?

 

Maybe we forget about using live sand in favor of a synthetic media?

 

If we use synthetic media + ammonium, do we bother adding any bacteria? Even a cup of water from an existing tank?

 

Do you propose that the revised experiment should look more like this:

• we fill both tanks with saltwater

• add synthetic bio-media

• add ammonium

then:

• top off tanks daily

• test ammonia, nitrite, and nitrate every day

• perform water changes on the test tank every other day

 

That sounds like a good plan to me. I would also suggest you test the water change water for N compounds before adding it (just because you never know...), and perhaps consider doing larger water changes.

 

Other options for NH4 are ammonium chloride and ammonium nitrate. The latter, of course, would confound your nitrate readings if you are interested in testing for those.

 

My rationale for suggesting sterile sand is that any time you start to involve live animals or bacteria it can vary your results even more...Rob replicated the experiment above using live sand and he got even more variation IIRC.

 

In any case, you don't need to introduce nitrifying bacteria from some outside source--they will literally appear out of thin air.

 

Interested to see what you find!

[seabass]

If we will not be using sand, wouldn't the surface area, weight, and lack of organic matter be more uniform if we used a plastic media like Nano-Balls?

I'm thinking about the 1,000 count box for each tank. Any thoughts before I place an order?

[Mr. Fosi]

... wouldn't the surface area, weight, and lack of organic matter be more uniform if we used a plastic media like Nano-Balls?

 

Yes, it would be more uniform.

 

If all you want to answer is "do waterchanges prolong the presence of detectable NH3", you could use them and be fairly uniform.

[seabass]

Thanks to everyone for your input. Psychosis and I have decided to proceed with the test using live sand as the bio-filter and food pellets as the ammonia source. We feel that this method provides reasonable control of the variables while retaining some of the natural processes that normally take place when cycling a new marine aquarium.

 

We recognize the benefits of tightly controlled variables, and encourage those interested to perform the test using some of these alternative methods (like ammonium versus ammonification, and plastic bio-balls verses live sand). In addition, the difference might be more definitive by performing even larger water changes. You are invited to follow along as we perform our test on this thread.