Nitrites starting to pick up, when should I do a water change?

Tyyrlym

Unless you change out 100% of the water you'll be leaving excess ammonia and nitrites in the tank for the bacteria to consume.

iamntbatman

It's up for debate, but I believe keeping your ammonia and nitrite levels as low as possible *can* prolong your cycle.

But, since you have live fish in the tank, keeping them happy and healthy is of utmost importance. I'd rather make my cycle take twice as long and have my fish live through it than kill them off trying to make the tank cycle faster.

Sj45

Just as I thought ammonia might be lowering (as you can see in my other post)...it didn't and I just did a 50% water change to reduce it from .50 or so to .25.

My Question:

Was a little concerned about when my nitrites might pick up. I am not using any "quick cycling" products such as bio-spora but it's been exactly 11 days and I still have no readings of nitrites. Should i worry?

Tyyrlym

No, it'll take some time. The initial colonies take time to grow, things will speed up and happen faster.

I'm curious as to why you believe this. Not trying to pick a fight, just curious.

iamntbatman

It would be impossible to measure all of the variables present that determine beneficial bacteria growth rates. The supply of ammonia (or nitrite, depending on the bacteria) is only one of these factors, and probably the only one we can measure reliably. If one of the other factors were to change, there could be potential for the bacteria to multiply at an increased rate. At that point, the supply of ammonia or nitrite in the tank would be a limiting factor on bacteria growth rate. If you had a higher concentration of ammonia, the bacteria would have been able to multiply faster.

As I've said before, all of that doesn't really matter much. If you're cycling fishless, there's really no point in doing water changes anyway since that's just extra work and costs extra resources. If you're cycling with fish, you absolutely want to be doing water changes to keep ammonia and nitrite levels low for the benefit of your fish.

Tyyrlym

I see what you're saying but I don't agree. Detectable ammonia and nitrites in the water are materials the bacteria cannot consume at the moment. While multiple conditions can affect bacterial growth many of the big ones are highly stable in an aquarium, the temperature isn't going to vary by more than a degree or so, pH is steady, flow is steady, etc. The only thing that's changing is ammonia or nitrite in the water which is built up excess that they cannot consume. The bacteria are already consuming food and making more bacteria as quickly as possible. While there could be other factors we don't monitor that are changing in a semi-closed system like an aquarium they are minimal.

Since what we're looking for is a sufficent number of bacteria to consume the ammonia and nitrites at the rate they are created in the aquarium a sudden dramatic rise in the number of bacteria to a level sufficent to consume 0.25 or 0.50 ppm of ammonia or nitrites rapidly would be the tank finishing cycling. If the bacteria populate enough to consume all the ammonia present in a tank your tank has cycled. If there are not enough to keep up with the fish they will not be able to eat themselves out of house and home because they will never able to keep up with production.

Look at it this way. Your tank is a table. A conveyor belt is bringing a constant stream of food to the table. A guy is sitting at this table eating as quickly as he can. The downside is to begin with he can't keep up. The food starts to back up on the table. New guys get added to the table from time to time but the food keeps piling up. Eventually someone comes along and takes away half the food piled on the table. Well the food doesn't stop coming, and the guys don't stop eating.

Here's the thing, the pile of food on the table, the ammonia and nitrite in our tanks, they're byproducts of what's really important. What's important is that conveyor that's bringing food to the table. If the guys around the table can keep up with it no food piles up. If they can't the food will pile up no matter how much of the excess you remove. I can remove 99% of the food from the table, but if the guys around it can't keep up with the conveyor they still won't be able to clean the table off. You see the conveyor keeps working at the same speed no matter what. It doesn't care what happens on the table, it keeps bringing the food. In our fish tanks our fish don't care what's happening with the ammonia levels. They keep on breathing, eating, and pooing no matter what. Their production is constant, until you have enough bacteria to consume all that waste they will never be able to remove all the ammonia and nitrites from the water.

Therefore water changes make no difference at all on cycling the tank. If you don't have enough bacteria ammonia levels will alway be > 0 and always on the rise. If you have enough bacteria to consume all the waste being made then guess what, it's cycled.

Like you said though, this is mostly academic because it makes no difference to fishless cycling where there are no fish requiring you to keep ammonia levels down. I do think it matters somewhat though because I have heard people hold off on water changes with fish-in cycling, or advise holding off on them, specifically to keep from prolonging a cycle. I think it's worth pointing out that it doesn't, and to keep on with the water changes for your fish's health.

WisFish

Using your analogy, water changes is like having someone from the restaurant coming in to remove half the uneaten food from in front of the guys. It will slow down the introduction of new guys because the guys that are there may not call in friends to help them eat. And since the conveyer belt is still bringing a constant supply of food, you want to encourage new guys to arrive. But more importantly, if the food backs up enough, the eaters will start to suffocate in all the food they are sitting in. (fish dying)

But you do want to keep more food in the room than the guys can eat so new guys arrive yet you don’t want to starve the guys you do have.

Tyyrlym

Except for the fact that there is still excess. Water changes, unless they are 100% water changes, can never remove all the excess pollutant in the water. Also, until your tank is cycled the conveyor continues to bring food faster than it can be eaten which means that even if you do a 100% water chance there will immediately be an excess of pollutant in the water because there are not enough bacteria to keep up with its production.

So there is always an excess of food for the new bacteria baring a total water change. Remember what we're dealing with her, microscopic bacteria, unicellular organisms. 0.1 ppm of ammonia might not seem like a lot, it might seem like there's not enough food to support new bacteria, but we're talking an amount of excess ammonia in the water that is thousands of times more massive than the bacteria and its getting greater all the time.

Since you can never remove 100% of the excess pollutants from the water by doing water changes the only way to get 100% out and actually start to starve bacteria is by the bacteria themselves consuming all the available excess pollutant. That's not a bad thing, it's a cycled tank.

iamntbatman

But if you remove 99% of the food on the table, and all you have left at that exact time slice is a single grape, that's not going to attract another guy to the table. Bacteria multiply by doubling; a single bacteria may not reproduce if there isn't enough excess ammonia in the water for it to warrant reproduction. Yes, there is always excess in the water, but I also believe if there is little enough of this excess bacteria may not multiply at the same rate they would if there was *more* excess.

Twistersmom

All this talk about food on the table is making me hungry!!! All my (fish in cycles) were complete in about three weeks, with a lot of water changes. I am now three weeks into my fishless cycle. My nitrites are off the chart, I am guessing it will take quite some time for them to drop down to zerro. This cycle is going to take alot longer, but my hopes are that by doing it this way, I will create a very large amount of bacteria and be able to introduce 8 or 10 fish at one time.