crushed corals or sand

[natan]

Hi all,

In order to reduce my nitrate problem I replaced about 70% of the crushed corals with sand (oh, it looks so brilliant now). It wasn't an easy process and everyone looks stressed out.

My main concern is this: isn't the removal of so much of the bio filter likely to cause nitrite problems (not to mention ammonia)?

I added a good load of Cycle formula to avoid the new tank syndrome and am still very concerned.

And to the question: is in general sand safer than the c.c.? Why?

 

[reeffreak]

Every fish and other inhabitants really should of been put in a holding tank and kept there until you were sure it didn't cause a cycle.It's possible/likely to start another cycle.Maybe adding the live bacteria will help it go quicker.

 

[Rcpilot]

I'd have done 25% at a time over about 2 months.

What's done is done though. Just keep an eye on your tank and if anything looks sick, check the water and be prepared to do a 25% water change. I'd keep some saltwater made up just in case.

 

[natan]

I have all the emergence measures in place.

What I don't understand is that people are cleaning their life rock, removing stuff from the glass, adding dead rock,..., and still I rarely see it mentioned that the new tank syndrome is a risk.

 

[natan]

There seems to be a trade off between the new tank syndrome and the concentration of nitrates.

 

[Bifferwine]

I think that more of your biofilter is in the live rock than in the sand. Did you use live sand to replace the crushed coral? If you used live sand rather than dry sand, the chances of another cycle starting is slim.

 

[reeffreak]

I forgot to answer your question on sand.Aragonite sand which I hope is what you have has superior buffering capacity over crush coral.Eventually crush coral loses that ability while aragonite sand doesn't.It doesn't trap debris and decaying matter like crush coral.Sand is better for sand sifting organisms and cleaners like gobies,pods,nassarius snails,worms etc.I believe in the long run it will cause you less headaches.

 

[fatman]

Freshly produced coral skeleton is aragonite. However it doesn't take long after a corals death to cause the aragonite turn into the standard calcite. They are the same chemical formula but in a different geometric arrangement. That difference makes aragonite able to dissolved at a tank pH just a little lower than is normally experienced in a tanks water. However in the deep layers of a deep sand bed the pH will drop low enough for the aragonite to dissolve putting calcium and trace elements back into water that were originally extracted by corals when building there skeletons. In some areas bordering reef lagoons aragonite is precipitated from marine water. This is the aragonite typically bought. Crushed coral is old coral skeletons, and sadly these old skeletons have already converted to calcite (calcium carbonate). Calcium carbonate does not dissolve at normal pH's experienced in a marine tank or even a sand bed therefore they supply no trace elements or calcium that can be utilized by tank inhabitants. Crushed corals are a good inert substrate as long as you stir them up and remove detritus regularly or if you can find finely crushed coral sand. However most is so course it just becomes a place for detritus to lodge and decompose. if your crushed coral was not in p[lace long or very deep there would not have been much bacteria to kill off. As Biffer said most of the bacteria in a tank is in the rock unless you have a mature deep sand bed then the majority will be in the sand bed. Deep sand beds start acting mature at around a year, but really take years, up to 8 or 10 to fully mature. The nitrifying bacteria mature at about a year the denitrifiers take the long periods of time to fully mature. Aragonite will dissolve enough that up to 25 percent per year will need to be replaced. About 5 percent is average though, unless you have very heavy calcium demands and large pH fluctuations. Low buffer capacities seem most to cause high amounts of dissolving of aragonte sands (and heavy feeding). If you do start to spike some nitrates, and definitely if you spike ammonia, you should use some Amquel or be prepared for doing ware change(s). If you have enough good live rock though you should need neither.

 

[natan]

Unfortunately I used dry sand. Fortunately I replaced less than 50% of the crushed corals. The latter are covering the bases of the life rocks. I'm stand by for any emergency within the next couple of days. I already added the Cycle formula and am recording nitrites continuously.

 

[Bifferwine]

I honestly don't think it will be a problem, it's good that you are ready to go with a water change, but I think you will be just fine.

 

[natan]

I have just detected a low level of nitrites. It is barely detectable (0.5-1 ppm) but positive (I used tap water as a negative control). If this is a sign of a new tank syndrome I want to wait. Isn't water change only gonna prolong the inevitable?

 

[fatman]

Inevitable? Inevitable what? It is not unusual any time you disturb a substrate bed for there to be a large bioload put on your system. Even vacumning the substrate out would have allowed a lot of nutrients in the substrate to enter the water rather than all being caught and removed. However, there is an active system working in your tank or you would first be reading ammonia not nitrites. It would, however, have been better if the nitrates had spiked instead of the nitrites. No tank inhabitant tolertae muv=ch in the way of nitrites. They should however be pretty short lived due to your live rock. Some people would call what your now having a mini cycle. It is however just a simple indicator that you have a young, still small but active biosystem that needs more development in order to handle large immediate changes. a water change would not hurt and could help a great deal in lowering stress and chances of death with your tank inhabitants if your system can not quickly turn the nitrites into nitrate. Amquel will detoxify the nitrite so as to help your fish but the biosystem will still need to change the nitrites to nitrate. Either way your biosystem will continue to develop as there will still be a imput of nutrients due to the inhabitants outputs and your food inputs not consumed by the inhabitants.

 

[natan]

I mean: in order to recover the system wouldn't it be unwise to remove any nitrites present - necessary for the growth of bacteria - even if the concentration is below say 3 ppm?

How long do mini-cycles "normally" last - relative to initial cycling?

Anyways, it looks today the nitrites are below 1 ppm (although still positive) and nitrates increased during the day. So I plan to do a 30% water change tomorrow.

 

[fatman]

You will always have ammonia, nitrites and nitrates. Often they will change from one to another so quickly they will not be detected and at other times they will be so low that they will not be detected, but once a body of oxygenated water has been exposed to the bacteria and any nutrients they will likely be their. They can handle quite a lot, like a o.5 pH change from their ideal in either direction and still feed and multiply. The different bacterias prefer different pH's and one needs an oxygen free environment but both conditions can be supplied without any heavy loads of nutrients. Whether those nutrients be in the form of ammonia, nitrite or nitrate. Keeping aquarium inhabitants is more important than trying to rush the full development of a bacteriological system in a tank. That full development takes time, rushing it does not work well. Important are dissolved oxygen and nutrients. It is hard to look at just nutrients and discuss bacteria as bacteria can have lots of food, but they also need oxygen. The higher the level of nutrients the lower the level of oxygen, the less further development of the bacteria. Moderation and patience works best. Build your system slow and added your stock slow and your system will be stronger and better able to accept rapid changes. Your system will continue to develop for years, meaning it will not reach the peak of its capacity for it's maximum load for years.