Has my cycle stalled?

[Darb21]

Using a shrimp to do the fishless cycle in a 29 gal. Started March 7th. Seeded with gravel from another tank on day 4. Ammonia started to come down while nitrIte and nitrAte both skyrocketed... these last few days, nitrIte has come way down and this morning nitrIte was .5. Odd thing is that nitrAte has plummeted from where it was too... Looks like I do have some brown algae growing in there too.

Is the cycle near complete with the brown algae eating all of my nitrAtes, or am I stalled?

 

[TomK2]

Are you using a quality liquid reagent test kit? When ammonia is zero, nitrites are zero, and you have seen a definite increase in nitrates, you are done. IME, the brown algae has always appeared a week or so before a cycle was complete.

 

[Darb21]

Are you using a quality liquid reagent test kit?

Yeah, the aquarium pharmaceuticals master test kit... its odd, because both nitrItes and nitrAtes both spiked really high, now both are coming way back down. I expected the nitrItes to come way back down and eventually to zero, but the nitrAtes too? I guess I'm just wondering if the brown algae is causing the decrease in nitrAtes...

 

[Purrbox]

Some kits will read Ammonia or Nitrites as Nitrates, making your Nitrate reading higher than it actually is. Not sure if the AP kit has this problem or not. You may also want to review the test kit instructions, as sometimes it can be easy to forget about one of the small steps (like shaking the reagent bottle before adding the drops) which can cause results to be off from what they should be.

 

[TomK2]

A declining nitrate level, in the absence of live plants or water changes, is suspicious of testkit or user error. Ammonia and nitrite can rise and fall, but nitrate is not converted to anything else, so that it should only rise. Yes, the nitrite and nitrate test share a common pathway, so that nitrite will show up on a nitrate test(but not the reverse until very high nitrate levels), but since the scales are different, it takes a lot of nitrite to alter the nitrate test. But even so, the nitrite is converted to nitrate, so there is no reason for the nitrate to drop. IMO, algae growth is not going to cause significant decreases in nitrate. For more info into the test kits, you can sheck out:

http://home.comcast.net/~tomstank/tomstank_files/page0018.htm

 

[Darb21]

Well, it looks like it is cycled for sure. Tests now show 0.0 Ammonia, 0.0 NitrItes, and about 40 NitrAtes... so thats good. Now on to fighting this brown algae... Anyone have any good tips on getting rid of the brown algae? Its getting all over the walls and the sand too...

 

[Purrbox]

If it brushes off easily it is diatoms. It's common in new tanks and will go away on it's own within a few weeks. If that's not quick enough for you, Otos apparently think it is quite the delicacy and will make short work of it.

 

[TomK2]

Yep, self limited. Pleco's find it irresistible too.

 

[arrow1234]

ok sorry for cutting in, but i have a question for the cycling,
why do you cycle the tank?
i though only new tank needs to be recycle

 

[TomK2]

arrow-
the "cycle" is that period of time when the tank's substrate and filters bio-media are growing bacteria that can convert ammonia into nitrate. Anything that disrupts the bacterial colonies from performing this task results in another "cycle", or elevated ammonia and nitrite levels. Darb has a "new" tank, meaning it has been up for a few weeks and the bacterial colonies are just now getting established. It typically takes 4 to 6 weeks for this to happen, if already colonized media is not added from an established tank.

 

[arrow1234]

ty tomk2,
so...cycle is for new tank only ? after that, we do NOT need to cycle the tank anymore. correct ?

however, if cycle is for the conversion from ammonia to nitrate, my theory is that this cycle should take place all the time because ammonia is generated from fish poop, and fish poop come from the fishes every minute....

or say it in other way, fishes keep making poop (all the time). the poop keep transforming into ammonia(all the time), the cycle should take place all the time to transform ammonia back to nitrite then nitrate.


or my other guess, the nitrate can avoid the generation of ammonia from poop

sry for this bs theory, i thnk i m wrong thou but just wanna know how stuff works

 

[europas_ice]

You can do a google search for "'fish tank cycle" and you'll find lots of articles talking about this, for example http://faq.thekrib.com/begin-cycling.html

As you say, in an established tank, there is a cycle going on all the time, converting the fish wastes from ammonia to nitrite to nitrate. But when we talk about "cycling the tank" we are talking about getting that cycle started. If you have a clean tank, fill it up with de-chlorinated water, and dump a fish in, there won't be a cycle. The ammonia levels will build up higher and higher until they kill the fish. To get the tank started cycling, there needs to be enough food (ammonia) for the bacteria, and they need a place to live. And (I've heard, haven't done this myself yet) it takes a couple months to grow all the bacteria that are important for keeping the water healthy for the fish.

In addition to needding to "cycle" the tank when it's new, you have to cycle the tank any time you (for some reason) kill off or remove all the good bacteria. (ie, tap water with chlorine will kill bacteria, and if you just throw out your filter material and put in fresh, you're throwing out tons of good bacterria.) This shouldn't happen though, if you know what you're doing. A good liquid reagent water test kit will help you keep tabs on the toxins in the water. HTH.

 

[TomK2]

The "cycle" is that period of time when the bacteria are not of sufficient quantity to prevent the "cycle" of high ammonia levels followed by high nitrite levels, then rising nitrate levels. If the "cycle" levels get high enough with fish in the tank, you get "new tank syndrome" or lots of fish death and disease. This cycle occurs predictably in all new aquariums.

But you are correct, after the initial high levels of ammonia and nitrite, ammonia is still constantly and rapidly coverted to nitrate without any detectable ammonia or nitrite levels. This would be the process of nitrification, and I suppose you could think of it as part of the nitrogen cycle. But in aquarium slang, the "cycle" is the period when bacteria can not convert ammonia and nitrite quickly enough to prevent high or detectable levels. Note that you can have a "cycle" in an established tank if something disrupts the bacterial colonies, such as a pH crash, antibiotic administration, or removing all the colonized biomedia at once.